The Titans Tower is the Teen Titans' base of operations, built by the Titans. It is located on an island in the Jump City bay. Each Titan has his or her own room. Its Main Ops room also serves triple-duty as a living room and kitchen. It also has training facilities both inside and outside, as well as a gym, for the Titans to stay in shape.
A similar version is built for the Titans East, but it has been built on the side of a cliff, not on an island, near the coast of Steel City. In Teen Titans: Trouble in Tokyo, the Tower's location (as well as the location of Jump City) is revealed to be near California.