These are the former big cat cages at the old LA Zoo. The old zoo exhibited tigers, lions, jaguar, and spotted hyena in these cages.
This information comes from an interview with former LA Zoo curator Michael Dee who worked in the old zoo area when it was a quarantine area for the current LA Zoo built in 1966 approximately a mile from this site.
I reviewed the Griffith Park Zoo and recounted my visit with Mike here:
http://www.zoochat.com/22/put-me-zoo-review-old-los-314434/