Okay Klaus, I'll be your Huckleberry and take a guess here. Two possibilities come to mind based on what you have said so far. (1) It is an observation dome to protect and display something and (2) a hotel with a monorail.
The first suggests that this is the museum, perhaps adjacent to Lake Armstrong (referenced by Riker in First Contact) that houses what is left of the Eagle landing site (since the top half of the landing module separated and returned to the command module) from the Apollo 11 mission, thereby preserving and displaying the first steps man took on the moon.
The second, with its reference to a hotel and monorail suggests that this is Disneyland Luna (just like Disneyland Paris, Disneyland Tokyo, and Disneyland Hong Kong).
My bets are on the first; it just feels more in keeping with this month's theme. Although, the idea of what an amusement park (or planet, Risa excepted, of course) in the Star Trek universe is interesting.