The Red Fort in Delhi was constructed between 1638 and 1648 on the orders of Mughal Emperor Shah Jahan. It contains halls for public and private audiences, marble palaces, private apartments, a mosque and gardens within its 124 acre grounds. The fort is surrounded by thick red sandstone walls that are up to 75 feet high and fortified with 21 towers and 7 gateways. Agra Fort has an irregular semicircular shape with its back protected by the Yamuna River. It has a massive western entrance called the Delhi Gate and is approached through a winding ramp.