Photo Postcard of the Main Allentown Post Office, 5th & Hamilton Streets The building was built by the Works Projects Administration (WPA) in 1933-1934 in an art deco style. The floor is adorned with handmade Mercer tiles from Doylestown. Muralist Gifford Reynolds Beal worked inside the building until 1939 portraying the Lehigh Valley's cultural and industrial history.