Urban Exploring in or near Riverside

I'm going back to Riverside from San Francisco and was wondering if anyone knew of any abandoned buildings or areas that not many people go to? I love exploring since there is an abundance of these locations around me and I like to see these places almost frozen in time. I've looked around Riverside and have only found graffiti waterfalls, the portal, and a bunker in Fontana. Does anyone know any other locations or at least clues on how to find them?

All aboard for a Day Out With Thomas

Day Out With Thomas 2015 is a fun-filled event that provides children of all ages the opportunity to climb aboard and take a 25-minute ride with Thomas and a 15-minute ride with Percy. Aspiring engineers and their families can also participate in tons of Thomas & Friends themed activities. November 7-8-11 and 14-15. Advance tickets are recommended and start at $19 for two and over. Advance ticket purchase is recommended. Purchase you tickets before September 1st and save!!