The Simi Hills are a rocky mountain range on the western edge of the San Fernando Valley, United States. They are almost entirely in Ventura County. Simi Valley lies to the north, and Chatsworth, Los Angeles, California lies to the east, over the border in Los Angeles city and county. The Simi Hills are the home of the Rocketdyne Santa Susana Field Laboratory where the first commercial nuclear reactor was operated, and the Ronald Reagan Presidential Library.

Ventura County, California