It’s an out-of-the-box undertaking. Ground has officially been broken in Saudi Arabia for what is expected to be the “world’s largest building.” The ambitious, $50 billion project — called the Mukaab — in the capital city, Riyadh, is part of a wave of futuristic construction across the Arab nation, the Sun reported. The skyline-redefining Mukaab will clock in at 1,300 feet high and 1,200 feet wide when completed — giving it enough volume to contain 20 Empire State Buildings, the outlet reported. Offering fine dining, retail space, offices and restaurants, the massive cube will be its own downtown-in-a-box with 2...