Smithsonian Institution Building

Smithsonian Institution Building
U.S. National Register of Historic Places
U.S. National Historic Landmark
The Castle
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Location	Washington, D.C.
Coordinates	38°53′19.49″N 77°1′33.59″W / 38.8887472°N 77.0259972°W / 38.8887472; -77.0259972Coordinates: 38°53′19.49″N 77°1′33.59″W / 38.8887472°N 77.0259972°W / 38.8887472; -77.0259972
Built	1849- 1855
Architect	James Renwick, Jr.
NRHP Reference #	66000867
Significant dates
Added to NRHP	October 15, 1966
Designated NHL	January 12, 1965

The Smithsonian Institution Building, located near the National Mall in Washington, D.C. behind the National Museum of African Art and the Sackler Gallery, houses the Smithsonian Institution's administrative offices and information center. The building is constructed of Seneca red sandstone in the faux Norman style (a 12th-century combination of late Romanesque and early Gothic motifs; built in the Gothic and Romanesque revival styles) and is nicknamed The Castle. It was designated a National Historic Landmark in 1965.

The Castle was the first Smithsonian building, designed by architect James Renwick, Jr., whose other works include St. Patrick's Cathedral in New York City and the Smithsonian's Renwick Gallery, also in Washington D.C. The building committee held a nationwide design competition in 1846 and selected Renwick's design by a unanimous vote. A cardboard model of Renwick's winning design survives and is on display in the Castle. Renwick was assisted by Robert Mills, particularly in the internal arrangement of the building.

Initially intended to be built in white marble, then in yellow sandstone, the architect and building committee finally settled on Seneca red sandstone from the Seneca Quarry in Montgomery County, Maryland. The redstone was substantially less expensive than granite or marble, and while initially easy to work, was found to harden to a satisfactory degree on exposure to the elements. Scholarly evidence indicates it is likely that slaves were employed at Seneca in quarrying stone for the Castle, though no evidence has surfaced that slaves were involved in the actual Castle construction.