Lake Elsinore "Tarzan" House
The fabled "Tarzan House" "Esther Williams House" (corrected by Harv Dykstra in comments) is a 1920s abandoned ranch style home that's perched high above the 15 freeway in Lake Elsinore with an amazing view of the valley & lake below. I've seen it from the freeway many times and had an opportunity to photograph it shortly before it was demolished in June 2015. Even in it's dilapidated state it's obvious this was an incredible home in its day - it's unfortunate it fell into such disrepair.
You can read about the demolition in an article on the Press Enterprise - http://www.pe.com/articles/property-770815-house-ranch.html