The Gotham Observatory was located on a hillside of Gotham City.
History[]
When Joker escaped from Arkham Asylum, he used the Gotham Observatory as the place to locate the satelite antena to broadcast his holiday program "Christmas With the Joker". When Batman and Robin located the source of the relay signal, Joker used the observatory's optical telescope as a cannon and attacked the duo, destroying part of the city in the process. Robin managed to sneak into the building and after destroying several Joker robots with machine guns, Robin destroyed the cannon, saving Batman and the whole city.