The United States’ largest airline is taking its base of operations to the nation’s tallest building. It was announced Monday that United Airlines will be moving its headquarters to Chicago’s Willis Tower. The airline giant signed a lease with Willis Tower that would last through 2028. Current plans to move its headquarters would see United taking over 16 floors, about 25% of the entire building. United’s Network Operations Center is already located within Willis Tower. Once the move is completed, 4,000 United Employees would be working in the general area, with 14,000 total employees working in the city and nearby areas. Willis Tower is currently the tallest building in the United States, but will soon be dethroned by New York’s new World Trade Center tower.