The Old Post Office and Customshouse is a historic site located at 281 Front Street, Key West, Florida, United States. On September 20, 1973, it was added to the U.S. National Register of Historic Places.
The Old Post Office and Customshouse currently serves as the Key West Museum of Art & History, which is one of several museums operated by the Key West Art & Historical Society. Exhibits include local history, famous personalities including Ernest Hemingway, maritime history, and works by local artists.
The building was designed by architect William Kerr, and was completed in 1891. The United States District Court for the Southern District of Florida met here from its completion until 1932, when the building was transferred to the United States Navy.