Located within the restored 1888 Federal Court House and U.S. Post Office building, the Jefferson Historical Museum houses four floors of historical exhibits that include art and antiquities, Civil War collections, Caddo Indian artifacts, early pioneer implements, early Texas textiles, children's toys and dolls, and genealogy archives as well as a gift shop. Behind the building is the R.D. Model Railroad Museum (see the entry for this museum).
The old court house was added to the National Register of Historic Places in 1969. It was designed in the Romanesque style by architect William A. Ferret. Originally the post office was located on the first floor. The building retains much of original architectural integrity and serves as important window into Jefferson's past.