This is called the AZ Island project, as designed by French architect Jean-Phillipe Zoppini. Over 1,300 feet long and 990 feet wide, the giant vessel is said to host 4,000 cabins plus its own "port" and other facilities, making it like a mini-city on the sea. Take that, Carnival Cruises!
Just imagine taking a vacation and visiting a variety of cities, going back to your own little floating city at night! This is only one of several similar concepts, which you can see on the not-so-greatly-designed but nonetheless interesting Megaships
Which one would you want to (at least temporarily) live on?