A hangar was a building used to hold aircraft. In the 1970s, with dinosaurs appearing in central London due to Whitaker's meddling, a Tyrannosaurus Rex was stunned by Mike Yates using a specialised stun gun and taken to an aircraft hangar on the edge of the Evacuated Zone.
It was chained up and an electrical field was placed around it to allow the Third Doctor to track the source of the time eddys. In order to prevent being found, Whitaker and his co-conspirator Sir Charles Grover had General Finch break the tyrannosaurus' chains.
Sarah Jane Smith was about to take photographs of the dinosaur when it awoke. She fled and it began destroying the inside of the hangar in an attempt to reach her. The Doctor helped her escape and it broke through one of the walls of the building. The dinosaur ultimately returned to its own time. (TV: Invasion of the Dinosaurs)