Jesus, some of you guys don't know WTF you're on about hahaha. It was a naval academy for k-12. Shut down in the 70's. They were GOING to use it as a Country Club but the economy started to tank.
More info here:
http://uberrhund.wordpress.com/2013/06/28/abandoned-lake-elsinore-military-school/
Also keep in mind, it's fenced and off limits, so any exploring would be illegal and you'd need to be pretty sneaky. Also, it's said to be haunted. woooooo