History of the Tregaron Estate

South facade of Parmelee mansion (originally “The Causeway” in 1912 — renamed “Tregaron Estate” in 1940)

North facade of Parmelee mansion (courtesy of American Institute of Architects)

North facade of Parmelee mansion.  Courtesy of the American Institute of Architects.

One hundred years in a nutshell:  The significant twentieth-century estate known as Tregaron, located in Washington, DC , lies between Cleveland Park and Woodley Park; it is bordered by Rock Creek Park on the east and Twin Oaks Estate on the west.  The 20-acre estate was first named The Causeway by its original owner, James Parmelee, in reference to the long stone bridge or causeway that leads to the mansion house (circa 1912) from Klingle Road.  The James and Alice Parmelee period was from 1911 to 1940.  After Parmelee and his wife passed away, the site was purchased by Ambassador Joseph Davies and his wife, Marjorie Merriweather Post.  Davies renamed the property Tregaron after the village in Wales where his mother was born.  After Davies died (1958), his heirs rented out parts of the property. The buildings and the entire 20-acre landscape became a DC landmark in 1979, the site is listed on the National Register of Historic Places and it is located in a historic district.  In 1980, the land was divided into two large lots and sold.  The Washington International School owns and occupies six acres in the northwest portion of the site.  The School owns all of the buildings at Tregaron.  The remaining undeveloped portion of the estate was owned by the Tregaron Limited Partnership (TLP) and it included the many notable landscape features.  In 2006, after more than 25 years of failed housing development attempts and having battled a very involved community and the Friends of Tregaron, TLP agreed to donate most all of its land to the Friends of Tregaron or a successor group. As a result of this stunning legal victory and global resolution, the Friends of Tregaron started a new non-profit organization, the Tregaron Conservancy.  In exchange for very limited development (three houses — two on Macomb Street, originally the “servants’ entrance” to the property — and one on open Klingle Road, next to the border with Twin Oaks Estate; all of three of these lots are on the property’s edges with minimal impact on the historic integrity), the Tregaron Limited Partnership donated 13 out of their 14 acres to the Tregaron Conservancy.  Those 13 acres will never be developed.  Instead, the land will remain as open green space.  Since 2005, the Conservancy has been hard at work, in the cumbersome and complicated process of restoring this important historic landscape; the organization has opened land it privately owns to the public for its use and enjoyment.

The History of Tregaron Estate (originally named The Causeway)

First, there was the Twin Oaks Estate:

Twin Oaks Estate (bulit 188-89), the summer residence of Gardiner Green Hubbard (Courtesy of the Library of Congress, Prints & Photographs Division)

Twin Oaks Estate (bulit 188-89), the summer residence of Gardiner Green Hubbard (Courtesy of the Library of Congress, Prints & Photographs Division)

Alexander Graham Bell standing, seated on the left his mother-in-law Gertrude McCurdy Hubbard and his wife, in white, Mabel Bell.  The Twin Oaks house is behind them.  (Courtesy of the Grosvenor Collection of the Library of Congress)

Alexander Graham Bell standing, seated on the left his mother-in-law Gertrude McCurdy Hubbard and his wife, in white, Mabel Bell. The Twin Oaks house is behind them. Courtesy of the Grosvenor Collection of the Library of Congress.

Around the same time that President Grover Cleveland was seeking refuge from the city by buying a summer home in what is now known as Cleveland Park, other Washingtonians were doing the same. In the 1880s, Gardiner Greene Hubbard, a wealthy Washington lawyer and founder of the National Geographic Society, purchased a tract of land between today’s Woodley Road and Macomb Street on which he eventually built an extensive and early Georgian Revival-style summer house which he named Twin Oaks. Modeled after the grand estates of Newport, Rhode Island and designed by the Boston architectural firm of Allen and Kenway, the gracious 26-room Twin Oaks commands its site high on a hill above the residential neighborhood.  Set on a wooded knoll, dropping steeply to two branches of Rock Creek, Twin Oaks was named after the two large oak trees that were joined at the base.  (These trees, or the Twin Oak, eventually landed on the Tregaron part of the property — ironically.)  Twin Oaks Estate was built in 1888-89 and served as a summer gathering place for the extended Hubbard family. One of Hubbard’s two daughters, Mabel, married Alexander Graham Bell, inventor of the telephone.  Hubbard’s other daughter Roberta married Charles J. Bell, the banker and cousin of the inventor.  Gardiner Greene Hubbard played a significant role in the invention and subsequent distribution of the telephone.  Upon his death, Hubbard’s property was divided between Roberta and Mabel.  Roberta kept the Twin Oaks Estate, while Mabel inherited half of the property — the undeveloped 20 acres to the east of Twin Oaks. Roberta Hubbard Bell kept the Twin Oaks estate in her family for quite some time.  Finally, after renting the property for 10 years, the Government of the Republic of China purchased the Twin Oaks Estate from Grace Hubbard Fortescue in 1947 to make it the official residence of each successive ROC ambassador.  Following the change in diplomatic relations between the ROC and the United States, Twin Oaks has changed owners.

Twin Oaks Estate in 2010.

Twin Oaks Estate in 2010.

The house has been owned by the Taiwan Government since 1982.  In 1986, Twin Oaks was placed on the National Register for Historic Sites.  The Taipei Economic and Cultural Representative Office in the U.S. maintains and operates Twin Oaks as a guest residence and center for diplomatic and social gatherings.   Twin Oaks survives as the one remaining example of late 19th-century summer house architecture in northwest Washington.


Next, came The Causeway Estate:

Tregaron Platt Photo

Charles Adams Platt

Meanwhile, Mabel Hubbard Bell or Mrs. Alexander Graham Bell sold her undeveloped share of the Twin Oaks property to James Parmelee, a successful financier from Cleveland, Ohio, in 1911.  Parmelee was looking to build a year round country house with views of the then new National Cathedral.  (Parmelee and his wife Alice Maury were major benefactors of the Cathedral and are buried in a crypt under the northwest pillar in the Great Crossing.)  They hired Charles Adams Platt, the premier architect of the Country House Movement in the United States, to design their home.  In 1900, Platt’s office was one of the New York firms that dominated the general development of American architecture, and his country houses and Georgian style mansions were regarded as the best American examples of their genre.  The estate, now known as Tregaron, was originally named “The Causeway” by Parmelee, in reference to the long, handsomely designed stone bridge that one crossed entering his estate from Klingle Road. A renowned architect, Charles Adams Platt designed the buildings and gardens to relate to each other as a single unit, often planning careful views from the buildings to specific landscape features, and vice versa. Platt realized the importance of viewing and designing the house and grounds as a unit. The Italian villa concept, which promoted the house and gardens as a single entity appealed to him.  Because of the importance of this planned single unit, the buildings AND the entire 20-acre landscape of the Causeway, now Tregaron Estate, are historically protected as a significant landmark. When the Parmalees purchased the property, the landscape was primarily woodland with a cow pasture bordering Klingle Road.  Platt drew on these elements, taking full advantage of surrounding views and vistas.  He chose the summit of the hill for the new house, and then designed a brick Georgian Revival mansion crowning the hill, in keeping with many of the District’s larger homes.  Leading up to the house was a long drive — the causeway — that began at Klingle Road, crossed a stream, and gracefully curved up the hill to the house. The mansion on the estate affords planned vistas to the north and south.The northern view shed looks down upon an undulating meadow to a bridle path and stream surrounded by mature trees. Also visible from this vantage point are small stone bridges and retaining walls.  The southern vista overlooks an open grassy lawn that is bordered by trees. Within view is the prominent causeway. Like the northern vista, stone hardscape features and the bridlepath are visible. There are also views to the west of the National Cathedral and to the east of the Soldier’s Home.

Ellen Biddle Shipman

Ellen Biddle Shipman

In 1912, Charles Platt brought in Ellen Biddle Shipman who is widely recognized for her contributions to the field of landscape architecture, particularly as a horticulturalist.  Tregaron was the second collaboration between Shipman and Platt (and is the only surviving one).  While Platt planned the circulation pattern for the site along with the formal gardens – it was Shipman who completed the plans in 1914.  She provided planting plans for the gardens and 20 acre grounds.  Platt and Shipman’s design was based largely on Beaux Arts principles, aligning the buildings and formal garden in axial relationships to each other, relying on design principles to optimize views and vistas.


The 1915 book American Country Houses of To-Day by Samuel Howe includes a lengthy description of The Causeway as an example of a desirable lifestyle.  The formal flower garden provided a place to walk and hold intimate conversations.  The sweeping lawn, beyond the formal garden and embraced at its lower end by the woodland/pond garden, provided more dramatic views of the larger landscape and the distant city.  Perhaps the landscape’s most intriguing feature was the bridle path, winding along the eastern edge of the property, crossing under the causeway and them meeting the drive at the property’s northern end.  Experienced as a whole, the estate’s landscape was more like that of an isolated country manor than of a house at the edge of the nation’s capital.

Plan for the Causeway landscape, ca. 1915, as illustrated in Samuel Howe's "American Country Houses To-Day"

Plan for the Causeway landscape, ca. 1915, as illustrated in Samuel Howe’s “American Country Houses To-Day”

The Causeway's south lawn with view of the Cathedral (1919); photo by Frances Benjamin Johnson (Library of Congress Collection)

The Causeway’s south lawn with view of the Cathedral (1919).  Photo from the Frances Benjamin Johnson Collection, Library of Congress

Platt’s plan for the landscape centered on using the existing bridle path as a spine, bringing together the various parts of the landscape.  The bridle path’s careful plantings marked it as a much more designed experience than most.  This was a constructed landscape inviting the visitor to be actively engaged with the site and the setting:  there was no single vantage point from which all views could be enjoyed.  As professor and author Thaisa Way writes:  “The Parmalees could ride horses or walk along the path, which began in the woodland garden following the edge of the hill to the opposite end of the estate.  The path predated the Shipman/Platt design, having originally circumnavigated the entire hill.  Shipman and Platt used the path to bring together the parts of this larger landscape, like gems on a necklace.”  The Causeway, with its beautiful landscape of diverse gardens, in many way exemplifies the nature of the partnership between Platt and Shipman.For more information on Platt, see Boston University Professor Keith N. Morgan’s books Charles A. Platt: Artist as Architect (MIT Press, 1985) and Shaping an American Landscape: The Art and Architecture of Charles A. Platt (University Press of New England, 1995).

Tregaron Platt Book In 1915, Ellen Shipman designed plantings around the pond, causeway, bridle path and brook. Her Christmas 1915 plan, presented to the Parmelees as a gift, incorporated the cow pasture, large existing trees, the stream, and the birdle path, the design carefully woven into the landscape.  Looking at the 1915 plan (which the Tregaron Conservancy follows closely for its restoration work), is noteworthy how the existing topography and waterway are used to create a naturalistic woodland of native and naturalized plants.  The path follows the course of the stream, with pockets of sun and water offering variety and interest.  This woodland garden was unlike Shipman’s other know garden designs, relying on an informal composition of naturalized plants around a pond.  Masses of color and texture were blended to form irregular beds enhancing the undulating topography, the site’s hydrology, and the existing trees.

Tregaron Tankard bookBy 1920, Ellen Biddle Shipman was completely independent, though she continued to collaborate with Platt on his residential projects. In 1927, the Parmalees hired Ellen Shipman again to design a wild garden for The Causeway.  Photographs of the woodland design show a complex scheme that had mixed drifts of ornamental exotics with indigenous varieties.  Period images show a woodland overstory shadowing large clumps of rhododendron and opening to sun-drenched clearings.  A rare sense of ease emanates from these garden pictures.  Shipman had a continuing relationship with the landscape, designing different, detailed sections of the property over many years.  For a complete list of plants that Shipman designed and incorporated into The Causeway (now Tregaron) landscape, see Ellen Biddle Shipman Plant List from 1919. Shipman’s gardens often appeared in magazines, including House Beautiful.  In 1933, House & Garden named her the “Dean of Women Landscape Architects.”  She lectured widely, and completed over 600 projects.  Shipman died in 1950 at the age of eighty.

Tregaron Thaisa Way BookAccording to Judith Tankard, landscape historian, writer and lecturer, “by 1950,most of the 600 gardens that Shipman had designed during her lifetime had changed beyond recognition.  Many were simply gone, and her work was quickly forgotten.  Ellen Shipman’s talent — an extraordinary talent — had escaped documentation in the annal of American landscape history.”  Her archives are at Cornell University.  For more information about Shipman, see The Gardens of Ellen Biddle Shipman by Judith B. Tankard (Sagapress, Inc., 1996).  In addition, Professor Thaisa Way’s book Unbounded Practice: Women and Landscape Architecture in the Early Twentieth Century (University of Virginia Press, 2009) is also an excellent resource on Ellen Shipman.


The Causeway is purchased by Ambassador Davies and is renamed Tregaron Estate:

After the death of the Parmelees, Ambassador Joseph Davies and his wife, Marjorie Merriweather Post, purchased The Causeway in 1940. They renamed the estate “Tregaron” after Davies’ mother’s ancestral home in Wales.  (“Tregaron” means ‘Caron’s Town’ after an early Welsh saint who founded the church in a small village in Wales.)  The Davieses made a few changes to the estate:  They hired a local architect to design a Russian dacha or folk house (reminiscent of their time in the U.S.S.R. when Joseph Davies was the U.S. Ambassador); once built, the Davieses set the dacha in a quadrant of the Shipman formal gardens to take advantage of the Cathedral views; they altered the landscape a bit by slightly regrading for the installation of a golf course; and they added fountains and painted the bottom of the lily pond turquoise. Over the years, the estate was the site of many prominent social gatherings, both during the Parmelees’ and the Davieses’ residences.  Newspaper articles from both eras describe many society gatherings, including teas, balls, and parties, held there, and notable visitors to the site included three U.S. Presidents (Roosevelt, Truman and Eisenhower).  Ambassador and Mrs. Davies also opened their home to benefit various charitable causes ranging from National Symphony performances to the American Merchant Marine Library.  A May 1944 article in Life magazine features Tregaron’s lovely mansion and elegant gardens.  The story was about an important party thrown by Ambassador Joseph Davies and his wife Marjorie Merriweather Post for the British, Chinese and Russian military missions.

The Davies-Post residence period at Tregaron spans from circa 1941 to 1958 which is marked by the death of Ambassador Davies.  He and Marjorie Merriweather Post divorced in 1955 at which time Mrs. Post moved to Hillwood just a short distance from Tregaron.  Davies stayed on at Tregaron following the end of their marriage; subsequent neglect and threats of overdevelopment prompted Cleveland Park neighbors to form the Friends of Tregaron in 1967.  In January 1979, Tregaron was designated a Historic Landmark of Washington, D.C., and in June 1990, Tregaron was listed in the National Register of Historic Places.   After 1958, Tregaron continued with limited use and very little upkeep for approximately twenty years as the disputes with the Davies heirs were settled.  From 1959 to 1979, the landscape received a far lesser degree of care and evolved without significant staffing and management.  With the Davies-Post departure and the ongoing troubles between the heirs, the land was open, but unoccupied and overlooked for a lengthy period.

Post Davies’ Era:  Tregaron is divided and threatened by housing development plans

In 1980, Tregaron was split into two large lots.  The Washington International School (WIS) — which had been renting the buildings for some time — purchased the six acres encompassing all of the historic buildings — the mansion, the greenhouse, the gardener’s cottage, the carriage house and the farmhouse.  The WIS property encompassed Tregaron’s hilltop.  The other portion of the property — 14 undeveloped acres — was purchased by the Tregaron Limited Partnership, an Israeli corporation.  The TLP land extended downslope to the property boundaries to the north, east and south.  Despite being warned that Tregaron Estate was a DC landmark and came with serious historical and legal restrictions, TLP insisted on trying to turn the open land into a large housing subdivision.  For over 40 years, there were numerous attempts to build multiple housing subdivisions on historic Tregaron Estate, ranging from 9 to 200 houses.  The Friends of Tregaron and the community fought off these threats, appearing in front of the DC Historic Preservation Review Board (HPRB) many times.  The HPRB has 18 different Tregaron case files.  Here are a few:

These attempts failed due to the strong historical and legal protections surrounding the landscape.  As a result of the efforts of the Friends of Tregaron, the non-profit organization that preceded the Tregaron Conservancy, and after years of negotiations, the private land owner agreed to donate 13 acres to be placed in a newly-formed land conservancy.  In exchange for the possibility of very limited development on the property’s edges with minimal impact on the historic integrity, the private owner Tregaron Limited Partnership, donated 13 out of their 14 acres to the Tregaron Conservancy. A legally binding agreement, signed January 24, 2006, by the Tregaron Limited Partnership, the Washington International School and the Friends of Tregaron Foundation sets forth the timing and details of the contribution of real property to the Tregaron Conservancy.  In addition, there are deed restrictions on the very limited development as well as conservation easements granted to the Tregaron Conservancy.  This land conservancy holds the deed to the property and is restoring, maintaining and operating the land.  The Tregaron Conservancy has chosen to open its privately held property to the public.

The magnificent and unique character of Tregaron Estate’s landscape and its important historical significance make all the labor and fundraising unquestionably worthwhile as the Conservancy restores and maintains this wonderful landmark.  The rehabilitation efforts since 2006 are proof enough that restoration of Ellen Biddle Shipman’s plans are possible and desirable.  As the years pass, challenges will continue, but the ongoing benefits to visitors will offset the work required to meet them.  As stewards of one of the few preserved Shipman designs anywhere, the Conservancy is fortunate to have — at last — the larger picture of her work and design philosophy to guide us as we continue our difficult and exciting preservation efforts at Tregaron.