When you enter Gotham City, you will be able to see a large welcome sign with Batman's symbol spraypainted in the corner. If you tap on the symbol, the ground will lift to reveal a small elevator built by Atlantis several years ago. If you type in "HJKY7" on the elevators keypad, you will go down 14 feet, directly outside Atlantis' hideout. This is where he works and spends most of his time.
Inside you will find three rooms. Technically, they are all one room, but they look so different, and are used so differently that it's hard to tell. Room one is the first area that you see when you enter the room. It is a table filled with tools and gadgets and tracking devices and parchment and book and magazine pages and several pictures. This is where Atlantis builds his inventions. Room two is where Atlantis Sleeps. In the center is a memory-foam bed with springs that can be adjusted by a remote. Next to it is a small nightstand where he keeps several items at night (his guns and knives). There is a small bathroom with a toilet and a sink closed off by a door. Room three, the kitchen, is where danny eats. It has several droors which are usually filled with meat or bread or chease. He also has a small bowl with fruit in it. If you twist around the bowl it will open the door to a small room which functions as a nuclear bunker with enough supplies to last 18 people for 30 years. It also functions as a state of the art shooting range and training facility. There is a tunnel underneath which leads to Alaska's Shed and the ICCOR HQ. This can be accessed by the AA Door, a large secret entrence that can only be used by Atlantis and Alaska.