Building a floating city also known as an aircraft carrier is hard as hell to do because the numbers are basically unfathomable. A basic aircraft carrier is made of 60,000 tons of steel, 4.5 acres of non-skid surface with four 325-foot catapults. The whole thing weighs 200 million pounds and takes five years to build and—get this—costs $5 billion at the very least. It’s a massive undertaking.
Source: Gizmodo – How to Build an Aircraft Carrier