Actually, Plumbrook has only been open to the public a couple of times. It had been 10 years since the last time they had an open house there. They do alot of rocket testing there and there's alot of volatile fuels on site. It's buried in the middle of a 20 square mile area for a reason, and because of that, it's not typically open to the public very often. You really have to keep your eyes open for an open house at Plumbrook as they are few and far between. NASA Glenn, which Plumbrook is a part of is open all the time for visitors though, and is a neat place to visit as well.