The building covering the piece of the crater floor was added in 1984. You can clearly see it in the upper part of the fenced in area.
![](http://www.wsmr.army.mil/paopage/Images/airGZ.jpg)
![](http://home1.gte.net/res0qiwd/trip/trinitite.JPG)
There is a small door that is opened to let people look inside and see some pieces of trinitite.
(This picture is actually one I took @ Trinity.)
Thanks.
The last time I was there was July 1995 on the 50th Anniversary. The other time was in the 80s. I do not recall the building. I may start doing drugs cause I really need an alibi for my memory.