The museum grounds comprises almost four acres and includes 11 exhibit buildings, six of which are historic.

This includes the Governor's Mansion built at its site in 1864 and listed in the National Register of Historic Places (NRHP).

It provides full-service research opportunities through its vast collections of rare books and special holdings of original documents, photographs, maps, and oral histories.

The Old Governor's Mansion was built in 1864 and was listed on the National Register of Historic Places in 1971.

[3] In front of the mansion are roses, of French "Boursault" type, descended from 1865 planting by Margaret McCormick, wife of the 2nd governor of the Arizona Territory (see photo including informational plaque).