Sycamore, IL, USA
I'm sure glad you had this question or I may never have seen that picture, or all 3 of them. It's interesting yet doesn't really say how they managed to build this. Getting materials up there must have been quite a challenge. Wonder if it was done with different sections being added on over a period of time or if this was the original plan and all constructed initially. Now, who can answer all these questions? It's an amazing place.
Serenity, it does look like pretty high ground. Maybe you should look into it, but make sure they have good internet connections first.