Each tower has 750,000 square feet of space with 50 floors and 10 units per floor of 15,000 square feet. There are 7.1 billion people in the world that would require 2.85 million towers of 500 units each to house the world's population at 5 people per unit. At a cost of $92 million per tower, it would cost over $262 trillion to house the entire world's population.