The administration building was built in 1936 and became a National Historic Landmark in 1987. It's the newest building to be added onto bathhouse row, and started out as the park's visitor center and museum in addition to being the administration building. It wasn't until 1989 when the visitor center and museum operations moved into the newly refurbished Fordyce Bathhouse. 

It was designed in 1936 by Charles Peterson and Thomas Vint of the Park Service's Eastern Planning Division. Peterson especially liked Spanish architecture as the roof is made of clay tiles and the entrance also features Spanish Baroque doors.The building does have one other function: in the basement there is a pump room and reservoir to help distribute the thermal spring water.