The concert is a large orchestra hall that only appears in the episode "Choir Boys."
It looks like it is built inside of a giant clam with the front entrance having the bow of a boat with windows and doors. There is also a wooden sign that reads the place's name on it.
Role in episode
Towards the end of the episode, the Bikini Bottom Men's Choir
perform here for a concert, while Squidward
gets to turn the pages of SpongeBob's songbook.