Union Oil Building, Santa Paula, CA
On the second floor of this building, above the Santa Paula Hardware Company and the US Post Office, Union Oil Co. was founded October 17, 1890; when corporate headquarters were moved to Los Angeles in 1900, production offices remained in Santa Paula. In 1950, the building became Union Oil Museum. In 1988, Unocal announced a $2million restoration of the site, creating the California Oil Museum of today.
Much of the stone in the Queen Anne building came from the Santa Paul creek, and the purple Sespe sandstone trim came from a Fillmore quarry. The first floor has permanent interactive exhibits centered on the oil industry in California and rooms for changing exhibits; upstairs the building has been restored to its 19th century corporate Board Room and office space. The rig room, a modern structure adjacent to the original building, has a working, restored 1890s oil rig!
See https://www.caoilmuseum.org/about for more photos and information about current exhibits. I have a personal preference for museums that are interesting for both kids and adults!