Located in downtown Martinez, the History Center houses the archives of the Contra Costa County Historical Society. Unlike a museum with artifacts, the Center has textual records such as court and early county records, photos, maps, letters, personal papers of local politicians such as Sheriff Veale, business records, and more. Some of the collection has been indexed and a search can be done on their website. A more extensive search can be done on their computers at the center.

The strengths of the collection are:

Original naturalization records for Contra Costa County
Property tax records from 1852 to about 1900
Probate packets
Contra Costa Gazette is digitized from 1860 to 1900
Thousands of photos and maps from all around the county

The library contains most of the books ever published about the county, obituary clippings, subject files for each town in the county, and a biography file. It is always a good idea when visiting a library or archive to ask about their vertical files or clipping files.These are often one-of-a-kind items.

The Center also have a great bookstore, selling most books available concerning Contra Costa County history and natural history. You can see a sampling here: cocohistory.ecrater.com.