The Batcave was the base of operations for those who used the mantle of Batman. A giant cave under Wayne Manor, the Batcave had become completely remodeled to become reminiscent of an underground bunker.
Ever since they became the Bat-People, the Miagani had inhabited a strange cave in Gotham City. When Wayne Manor was built over the cave, the bats were killed using owls, only the giant prehistoric bats survived. Around the early 1900s, the Miagani were assimilated into American culture and traces of them were forgotten.
The cave was generally unused for over one hundred years until Bruce Wayne became the Batman. Using it as a base of operations for his vigilantism, Wayne converted the Cave to fit his mechanics shop, the Batcave, filing cabinets, computers and an arsenal of weapons. The Batcave was briefly abandoned again by Richard Grayson during his period as Batman, though within eight months it was once again operational.
Following the loss of Wayne Manor after Wayne Enterprises was bought out by Gotham Council and converted into Arkham Manor. Bruce and the rest of the Bat Family still operated out of the Batcave after sealing off all entrances into the cave itself.
Even with the loss of Bruce. Alfred, Tim and Penny still operated out of the cave even with the manor in disrepair and the Bat family without a Batman.
After an explosion at the Power International Hadron-Collider. Bruce Wayne while on a visit to the facility emerged from the rubble, bloody and battered but with his memory fully restored. He then requested to a very emotional Alfred to open up The Batcave.
After Bruce Wayne's memory had been fully restored, he entered a secret compartment within the cave itself to retrieve a new prototype Batsuit. He then left to help Jim Gordon defeat Mr Bloom.
Following the defeat of Mr Bloom and Gordon retiring from the role as Batman. Bruce stored Jim's Mecha-Batsuit within the cave, while planning to upgrade and enhance the system within over time.