The Arcanium
Upon the Bureau's formation in the 70s The Arcanium was stocked with centuries worth of valuable knowledge relevant to the Paranormal world as well as a variety of powerful artifacts intended to aid its cause. Since then The Arcanium's content has grown exponentially and boasts one of the largest collections in the world. Agents returning from missions often deposit otherwise useless artifacts or information here whereupon they may also be withdrawn from those departing on new ones.
There is also a door that leads to Mordecai's Room