This 11.8-acre site, encompasses 11 historic buildings, located on 23rd Street, NW, across from the Department of State’s headquarters, is one of the highest points in the city’s original plan and became the  home of the country’s original Naval Observatory, completed in 1844 and now a National Historic Landmark.  The Observatory became obsolete when a new observatory was erected off Massachusetts Avenue.  During World War II, the site was occupied by the Office of Strategic Services which  subsequently became the Central Intelligence Agency.

The CIA moved to its new headquarters in Langley, VA in 1961, but the Navy maintained a presence on the site until 2012.  In 2005 the Department of Defense declared the site surplus and transferred it to the Department of State for its consolidation efforts in eliminating numerous rental facilities.  With the support of the Committee of 100, the DC Historic Preservation Review Board in 2016 designated the site as the Observatory Hill Historic District, which in 2017 was listed on the National Register of Historic Places.

In 2014 consultations were initiated to develop a master plan for the State Department’s use of the site, which initially contemplated the erection of 1.2 million sq. ft. of new space in several massive office buildings.  The Observatory is to be renovated and used for special events and meetings.  The Committee of 100’s position is that as many of the historic buildings  as possible should be preserved and reused, and that new buildings should be located and scaled to respect and complement the historic structures and landscape.  The Committee has actively participated and commented in consultation meetings on the development of the site.  There has been some progress in the reduction in the scale of proposed development and the location and size of new structures on the site.

In the absence of Congressional funding, there has thus far been no further progress in development of the site.


Document Library

Observatory Hill Campus


C100 Comments HPRB Observatory Hill Historic District

Richard Busch

The Committee of 100 supports the recommendation of the DC Historic Preservation Office Staff Report, prepared by Ms. Anne Brockett and Dr. Ruth Trocolli, that Observatory Hill be designated an historic district in the D.C. Inventory of Historic Sites, and we further support its nomination to the National Register of Historic Places for listing as a district of national importance.

Date added: October 27, 2016

C100 Comments On Potomac Hill Development Alternatives Matrix Of Effects And Modified Alternative B

Nancy MacWood

The Committee of 100 on the Federal City offers comments in the ongoing Section 106 review for the development of a Potomac Hill Campus Master Plan.

Date added: March 21, 2016

Nancy Witherell Potomac Hill Historic Nomination

Nancy MacWood

As a Consulting Party to the ongoing Section 106 Review of the Potomac Hill Campus Master Plan, the Committee of 100 on the Federal City supports the single comprehensive nomination for the site.

Date added: June 4, 2015

C100 Comments on Potomac Hill Campus Master Plan Section 106 Review

Nancy MacWood

The historic buildings on the Potomac Hill campus, including as much as possible of the existing plan, landscape and open space of the site, should be preserved and protected, and the scale, extent and design of any new construction on the site should respect these structures and not diminish their prominence and interrelationships.

Date added: February 23, 2015