Pangeos - The $8 billion turtle-shaped "terayacht"
This thing is insane. 550m (1,800ft) long and 600m (2,100ft) wide, with accommodation for 60,000 people, and space for airplanes. Not sure why it's called a yacht, though. I thought yachts were supposed to be smaller than ships.
https://www.youtube.com/watch?v=XT_3YmlXvOI
https://www.pangeosyacht.com/projects