I would guess (assuming Ye Olde Moonbatte is around 6' tall) that it's around 30 feet in diameter. It takes up most of the floor in one end of a large hall. They probably move it around on a flatbed sedan chair . . . .
A convent in the south part of our county has a genuine, inlaid stone outdoor labyrinth, out in the woods. It is a wonderful experience to be in nature and walk it. They even keep it illuminated at night, which is when I walked it the first time, and had an illuminating experience when my shadow blocked out the night lights as I walked the path the sudden panic of whether I was still on the right path was replaced by the scripture "a lamp unto my feet" flooding over me.