Officer's Quarters 3 was built in 1870, possibly in March, which would make it the first of the officers' houses to be completed. The house was the fort commander's residence until Officer's Quarters 1 and 2 were finished. The building has a total of five rooms, as it lacks a second floor. The two structures making up Officer's Quarters 7 were built from 1870 to 1877 to house field officers and their families. The buildings form a duplex stand to the same height and have two fireplaces each. A porch connects the between the buildings. On July 13, 1990, the E.H. Danner Museum of Telephony, part of the West Texas Collection of Angelo State University, was opened in the building.