Red fort of Agra is popularly known as Agra fort. It is one of the important monuments of India. This monument is in the Agra city of the state of Uttar Pradesh. Agra Fort, an excellent example of Mughal architecture, is one of the UNESCO World Heritage Sites in India. This 16th-century Mughal monument is made of red sandstone and it encompasses within its 2.5-km-long enclosure walls, the imperial city of the Mughal rulers. There are a number of exquisite buildings like Moti Masjid - a white marble mosque akin to a perfect pearl; Diwan-E-Am, Diwan-E-Khaas, Musamman Burj - where Mughal Emperor Shah Jahan died in 1666 A.D., Jahangir's Palace, Khaas Mahal and Sheesh Mahal etc. The construction of the fort was started around 1565, when the initial structures were built by the Mughal Emperor Akbar. This work was subsequently taken over by his grandson Shah Jahan, who added most of the marble creations to the fort. It is crescent shaped, flattened on the east with a long, nearly straight wall facing the river. The fort had originally four gates, two of which were later walled up.