The 1857 U.S. Federal Building
The Old U.S. Federal Building built in 1857 to serve Galveston, at that time Largest City in Texas and 3rd largest Port in the U.S.  It was the first non-military federal building in Texas.  This building housed Customs, the U.S. Post Office, and Federal Courts, among other things. 

This building was dedicated as one of the 13 historical Customs Houses in the United States and is featured on a commemorative United States postcard. It has been restored by the U.S. Government. Today, it houses the administrative offices of the Galveston Historical Foundation.