It seems that about every 20 years, the museum has outgrown its facilities and finds itself in desperate need of expansion. Because the museum building is land-locked, expansion of Harmon Hall was not an option. So in 1998, the historical society purchased the former Lebanon Post Office next door to Harmon Hall. It will provide the needed space in which to continue the tradition of presenting, preserving and storing one of the finest county museum archival and three-dimensional collections in the United States. Renovation began soon thereafter. In 2009 the main room of thePost Office was upgraded with new windows, drapes, new counterwork, a kitchen was installed, additional overhead lighting was installed, the floor was refinished and the room was repainted.

Finally, a large mural depicting early Warren County aviation pioneers was painted in the public entry hall of the building as well. This renovation also took place in the basement of the building where we put in a large temperature and humidity controlled vault, two additional storage rooms, and a large office and work area for our Curator, along with a bathroom. An integral enclosed and heated concourse connects this building to the basement floor of the Harmon Hall building.

The large room on the main floor is available for all sorts of rental and meeting events. It will seat 150-180 people. The building is handicapped accessible with a ramp from the rear entrance. This entrance is also for use for caterers and for folks to set up events.

The Post Office Building was built by the WPA in 1935.