I really want to check it out, since my hometown also has a surreal underground city of its own. Except ours was because the plague hit the town so bad that they just built a new town on top.
That was closed for about three years. I don't think they've reopened it yet.
Also, it's just some dirty underground rooms.
I heard it was supposed to be the "Dillinger-Escape-Plan" of Mao, for unsecure times...
It's even mentioned in the Lonely-Planet travelguide. Unfortunately the entrance for tour-visits is closed since more than 2 years.