Again you travel through winding tunnels for quite a long time, until a dim light begins to grow up ahead. Wisp hoots a low warning, and you slow...creeping up until overcast daylight is streaming in through the cave mouth.
You peek out.
You are on a ledge overlooking a massive crater surrounded by towering needle-like spires of orange rock. In the crater below, about forty or fifty feet down, you see a startling and awe-inspiring sight--many of them, to be exact! Throngs of people are everywhere down in the crater, of varying and spectacularly eccentric appearance. Many wear wizardly robes, but most are dressed much more flamboyantly.
There are a large number of cloth-tented stalls at the center of the crater, a circular area--nearly 200' feet across--as smooth as polished glass, an amphitheater packed with spectators, and an amazing number and variety of Leomund's Secure Shelters all clustered in one region of the crater.
Down and to the left there is a sudden dull BOOOOMMM!!! as a fireball erupts against the crater wall, answered by a cheering crowd. Then an even-larger explosion, and the crowd roars again.
A rock ledge snakes down the crater wall to your right...
Tall magic-one, hoots Wisp, What is this place?