It's got everything you could ever need. A theme park (complete with ferris wheel and roller coasters), a few dozen holotheatres, an ice rink, pod-racing circuit, aquarium, planetarium, more food and drink places than anyone knows what to do with, recreation centers... Pretty much anything and everything imaginable. There's a reason it was built 19km long after all.
Oh, and it's a warship too... there is that. But minor details.