The San Diego Air & Space Museum Gillespie Field Annex, located at 335 Kenney Street in El Cajon, California, serves as an extension of the main museum in Balboa Park . Established in 1993, the annex was created to accommodate the museum's expanding collection of aircraft and to provide space for restoration projects . Visitors to the annex can explore a diverse array of historic aircraft, including Cold War-era jets like the F-14 Tomcat and MiG-21bis, as well as unique exhibits such as the Convair SM-65E Atlas Intercontinental Ballistic Missile . The facility also houses a restoration workshop where skilled volunteers work on preserving and replicating vintage aircraft . Open to the public Wednesday through Sunday from 9:00 am to 4:00 pm, the Gillespie Field Annex offers aviation enthusiasts and history buffs an opportunity to delve deeper into the rich tapestry of aerospace history .