Agra Fort is a historical fort in the city of Agra in India. It was the main residence of the emperors of the Mughal Dynasty till 1638, when the capital was shifted from Agra to Delhi. The Agra fort is a UNESCO World Heritage site.It is about 2.5 km northwest of its more famous sister monument, the Taj Mahal. The fort can be more accurately described as a walled city.[citation needed]