The concept design of the ship Princess Kaguya has been carried out in cooperation with one of the top cruise ship building yards in the world, Aker Yards Cruise & Ferries (www.akeryards.com).

The size of the ship, 450,000GT, 505m length, 58m breadth hull, 20 decks, was first determined as an adequate level as defined by the requirement to have the “functions of a city”.
The highest priority was the functionality of the vessel so the appearance of the ship is in no way eccentric, and remains orthodox.
Trial speed is 22kn, which is more or less standard, however if one considers the grand size of the ship, its speed is nothing but surprising.
The largest allocation of floor space on the ship is the multi-purpose hall. This awesome floor space of 7,000 square meters is essential for various kinds of events to be held. It is about 10 times bigger than any of the halls in the hotels, and is capable of holding any kind of trade show, convention, in-door sport event, etc.
Three different class hotels, each with 1,200 rooms.
The size of the shopping mall was something also not to be compromised. A spectacular 300m long, 16m wide, 18.4m high atrium, to hold about the same number of shops as in a department store.
The building has not yet started but with a solid investment team I can’t see any reason why this shouldn’t become a reality.
More info and specifications [Source: princesskaguya.com]
Update: Royal Caribbean have already ordered a 360m length, 73m heigh ship named Genesis which will be ready for launch in 2009. The massive vessel weighs 12 times the Eiffel tower and will have a capacity of 5400 passengers. Until Princess Kaguya sets “sail” it will be the worlds largest-ever cruise ship.