Building at 1644 Main Street, also known as Tapp's Department Store, is a historic commercial building located at Columbia, South Carolina. It was built in 1940, and enlarged in 1950. It is a five- to seven-story, Depression Modern building faced in stucco and dark tremolite stone. Above the main entrance is a distinctive clock face and a sign with large freestanding letters. Tapp's Department Store closed in 1995. It was added to the National Register of Historic Places in 1979.