How do you get interesting photos of places that are hard to get into? My suggestion is get involved with groups that have regular photowalks. Check their schedules for events that would be of interest to you. Groups that have photowalks are camera clubs, private instructors and camera stores.
For this and a few other photos on this page, I attended a photowalk with Creve Coeur Camera. They have a very full schedule of classes and photowalks around the St. Louis area. Here we went to Creve Coeur Airport where the owners of these planes brought them out of their hangers so our group could photograph the planes on the ground and in the air. You could not get this type of access on your own.