Main Interior Building

	US Department of the Interior Building
	U.S. National Register of Historic Places
	Main Interior Building viewed from the south with the José Artigas statue in the foreground in 2005
Location	18th and C Sts. NW, Washington, D.C., U.S.
Coordinates	38°53′38″N 77°2′33″W / 38.89389°N 77.04250°W
Area	5 acres (2.0 ha)
Built	1936
Architect	Waddy Butler Wood, et al.
NRHP reference No.	86002898
Added to NRHP	November 10, 1986

The Main Interior Building, officially known as the Stewart Lee Udall Department of the Interior Building, located in Washington, D.C., is the headquarters of the United States Department of the Interior.

Located in the Foggy Bottom neighborhood, it is bounded by 19th Street NW on the west, 18th Street NW on the east, E Street NW on the north, C Street NW on the south, and Virginia Avenue on the southwest. Although the building takes up the entire block, the address is "1849 C Street, NW" to commemorate the founding of the Department of Interior in 1849. To the east is DAR Constitution Hall, the headquarters of the Daughters of the American Revolution, as well as the World Resources Institute and the American Red Cross National Headquarters. To the west is the Office of Personnel Management headquarters. To the north is Rawlins Park, which includes at its eastern end a statue of Major General John A. Rawlins, and Triangle Park is to the south.

The building includes offices of the Secretary of the Interior and major bureaus with their employees. It includes the Interior Museum and Interior Library.