This location is mentioned in the game's files, but doesn't seem to be on the map. As noted on the main site, it's probably a reference to Batman Forever, where the Riddler had his hideout. There doesn't seem to be any further clues in the game's coding, so this one seems to be a complete unknown. One option is the so-called Developers Rooms, but this far from certain as that area looks more like an office than a hotel.