Green Arrow's original base, located under the old Queen Estate. Green Arrow, with his sidekick Speedy, spent quite a bit of time in the Arrowcave. The Arrowcave, much like the Batcave, was used as a place to plan missions, and patrols, a place to keep their trick arrows, and other equipment; such as the Arrowcar, and Arrowboat. It has a trophy room, much like the Batcave, which is a collection of many things from Green Arrow's many adventures. One of the artifacts in the trophy room is a giant arrow. According to Roy Harper, it was first called the Arrowcave by Dick Grayson.
The Arrowcave was abandoned when Oliver lost his fortune, and with that the Queen Estate. The Arrowcave was last seen when Green Arrow and Arsenal went in search of Green Arrow's lost things, and during this journey they visited the Arrowcave. It still had power, because of the old generators. It had been inhabited by Solomon Grundy.
Injustice: Gods Among Us
In the video game tie in comic for Injustice: Gods Among Us, Green Arrow manages to capture Harley Quinn after Superman murders The Joker. Fearing that she will be in danger and not wanting Superman to do more things he'll regret later, Arrow takes her to the Arrowcave. She thinks it's a stupid name and that it should be rechristened "The Quiver" or something. Arrow, after a pause, says that it's a good suggestion.