The 11th Precinct is a police headquarters in New York City. It appears in every episode. Its structure was created in 1907. ("Pushing Buttons") Its first appearance is in the Season One episode "Pilot".
Rooms
The major rooms in the precinct building consist of the "bullpen" where the detectives desks, including Detective Bell's are located, Captain Gregson's office, meeting rooms and an interrogation room.
Multiple holding cells are also located in the building as is a storage area that is something used by Sherlock Holmes and Joan Watson as a temporary office while they work on cases. There are many other rooms such as evidence lockers. The building contains the offices of other divisions such as Property Crimes headed by Detective Mason. ("Pushing Buttons")