Funnily enough, when I was looking for links for the post, I discovered that they opened up a new section just a couple of years ago! Access to GB is still very restricted though to try to preserve the fragile structures. Reply
Taking One Day At A Time 
Wonder if there are any changes in these underground spaces over the last 20 years
Funnily enough, when I was looking for links for the post, I discovered that they opened up a new section just a couple of years ago! Access to GB is still very restricted though to try to preserve the fragile structures.