This looks like it was the entrance shed for the area at some point in the past, maybe even a small shop. But nature is reclaiming the spot. As always in the wild, even on cement, watch for vermin and varmints.
WE SUPPORT OUR STATE PARKS! In our strong desire to show our continuing support for our state parks, ALL geocachers must pay the entrance fee or show your Texas State Parks Pass in order to log this cache! By doing so, we will help geocaching continue to be a readily accepted use of Texas State Parks by parks management. This cache has been approved by the San Angelo State Park Management for placement in the park, with the typed permit on file at the Main Gate.