Overview: If you've ever wondered what California looked like 1,000 years ago, a trip to Carrizo Plain National Monument will take you back in time. About 250,000 acres are protected at the national monument, preserving California's largest, native remaining grasslands. From amazing wildlife to ancient signs of native people dating back 2000 years B.C., Carrizo Plain is a land frozen in time and a look into California's past that is now long gone.