As work on Project Apollo got underway, Southern California became a center of program activity. North American assembled the command and service modules at its Downey plant, with astronauts dropping by to assist with component testing and cockpit design. A separate North American facility at Seal Beach was used to manufacture the second Saturn stage. In Canoga Park, North American's Rocketdyne division was working on the Saturn engines, and near Santa Monica, Douglas was manufacturing the third Saturn stage.