The San Diego Reader has an interesting article on San Diego’s Secret Missile-Testing Sites. A bit long, but interesting. The area is question, "best described as the land east of I-15 ringed by Tierrasanta, Santee, the Sycamore Canyon/Goodan Ranch Open-Space Preserve, Poway, and Scripps Ranch," was a part of the old Camp Elliott, most of which became the Miramar Naval Air Station. The author, Moss Gropen, describes how he uncovered the hidden history of the facility. He enlisted the aid of 'B.R.' an urban explorer who has crawled and climbed through the area, and the descriptions are fascinating.
In the mid-50's, the site served as a static test site for Atlas ICBMs. It later supported Stingers, Tomahawks, and electro-magnetic guns. The facility even was the home to some Project Orion work, although the actual testing of the prototype occurred off of Point Loma.
The comments to the article were also good, and included links to other references:
(hat tip to sandog on TRF)