Old Naval Observatory

Old Naval Observatory
U.S. National Register of Historic Places
U.S. National Historic Landmark
Show map of Central Washington, D.C. Show map of the District of Columbia Show map of the United States
Location	23rd Street and E Street, N.W., Washington, D.C.
Coordinates	38°53′42″N 77°03′05″W / 38.895103°N 77.0514428°W / 38.895103; -77.0514428 (Old Naval Observatory)
Built	1844 (1844)
Architect	James Melville Gilliss
NRHP reference No.	66000864
Significant dates
Added to NRHP	October 15, 1966[1]
Designated NHL	January 12, 1965[2]

The Old Naval Observatory is a historic site at 23rd and E Street in Northwest, Washington, D.C. It is where the United States Naval Observatory was located from 1844 to 1893, when it moved to its present grounds. The original observatory building, built 1839-40, still stands, and is a designated National Historic Landmark as of 1965.^[2] The Washington meridian of 1850 passes through the Observatory.

The campus around the old observatory is split into two parts: the Potomac Annex to the east (where the observatory stands) and the E Street Complex, also known as Navy Hill, to the west.^[3] These two parts are separated geographically as the Potomac Annex is at the top of the hill, while the E Street Complex is farther down. The E Street Complex is also designated as a National Historical Landmark as of December 14, 2016.^[4]

The campus for many years housed the Navy's Bureau of Medicine and Surgery, which moved out in 2012. The property has been taken over by the State Department.