Royal Caribbean is building the world's largest cruise ship, which will be a city in its own right with seven different neighborhoods and a central public space/urban park.
"Royal Caribbean's new boat is big. Really big. The "Project Genesis" cruise liner, currently being constructed, will be 43% larger than the Queen Mary II, currently the world's largest ship. 1,180 feet long and weighing 220,000 tons, it'll be able to carry more people from New Jersey down to the Caribbean than any ship before it.
5,400 people, to be exact. The ship is so large that it has a "Central Park" the size of a football field in the middle, its own gigantic amphitheatre, and seven different "neighborhoods" that people will stay on."