This vertical rotating parking lot saves space and helps make parking more efficient. Drivers simply call an available parking spot down with the touch of a button, park in the slot, and the machine does the rest. The 39-foot-high vertical rotating parking lot installed in China's Nanjing occupies only two parking spaces in width but has six floors and can hold 12 cars. A giant motor rotates the system when another driver wants to park or when someone wants to leave.