The Animus is a Special place created by the Keydariens. Whenever your in a diffrent world (expect on Earth) there is a portal on that world and when you go through the portal, you'll end up here. The Animus acts as a gateway that safely takes people back to Earth. While in the Animus, your immuned to aging and death and any act of violence while inside the Animus wont hurt anybody. This dosen't mean you stay here as much as you like. This place is only design to take people from their world, to the real world and if you stay in the Animus for too long, you'll automaticly be teleported to the real world. Another way to go to the real world is by simply going through one of the doors that apper on the walls of the Animus. It dosen't matter what door you go through as they all take you to the same location.