Placer County California (Historic Districts) has 5 places on the National Register of Historic Places including 4 places of Statewide significance. Significant places include Dutch Flat Historic District, Old Auburn Historic District, Outlet Gates and Gatekeeper's Cabin and Summit Soda Springs and Outlet Gates and Gatekeeper's Cabin.
The famous person Mark Hopkins is associated with one of more of the Placer County historic places.
Some of the country's most noteable architects helped create the Placer County places including Unkown. Prominent architectural styles found in Placer Country are .