Batcave

The Batcave is the secret headquarters of Batman (Bruce Wayne), consisting of a series of subterranean caves beneath his residence, Wayne Manor.

History
As Robin accessed the Justice League database with ease, he claimed it was the "same system as the Batcave", which showed he can access the cave at will.

While Robin was training presumably in Wayne Manor, a glimpse of the cave was viewed with Batman watching on the monitor.