It was on one of the trails in the Torrey Pines Natural Reserve in San Diego. The south part of the Reserve is next to the Torrey Pines Golf Course where they play a pro tournament each year. I think the door was put there to keep people off the trail next to the course where they'd get a free peek of Tiger Woods and company. It was sure an eye-catcher for me and other people hiking in the Reserve.
Nice job with the train shot. The door and the round window are very cool!