Get a few of your friends together and pretend to be from a paranormal society. Do some research, find out who the buildings belong to, call the agency up and ask for permission to conduct a study on the building. Ask them if you could get a guide to show you around and a lot of other stuff. Get yourself a rudimentary paranormal study kit and do a study while you are there. It may very well get you into the place, LEGALLY, and you could have a lot of fun conducting the research, plus who knows what it might uncover.
Can you tell I've used that cover story before??? I picked up some interesting rumblings on EVP at Lambertville school, nothing conclusive but hey, it was fun, plus i can say I did something