With the Taj Mahal overshadowing it, one can easily forget that Agra has one of the finest Mughal forts in India. Construction of the massive red-sandstone fort, on the bank of the Yamuna River, was begun by Emperor Akbar in 1565. Further additions were made, particularly by his grandson Shah Jahan, using his favourite building material – white marble. The fort was built primarily as a military structure, but Shah Jahan transformed it into a palace, and later it became his gilded prison for eight years after his son Aurangzeb seized power in 1658. The ear-shaped fort’s colossal double walls rise over 20m in height and measure 2.5km in circumference. The Yamuna River originally flowed along the straight eastern edge of the fort, and the emperors had their own bathing ghats here. It contains a maze of buildings, forming a city within a city, including vast underground sections, though many of the structures were destroyed over the years by Nadir Shah, the Marathas, the Jats and finally the British, who used the fort as a garrison. Even today, much of the fort is used by the military and so is off-limits to the general public. The Amar Singh Gate to the south is the sole entry point to the fort these days and where you buy your entrance ticket. Its dogleg design was meant to confuse attackers who made it past the first line of defence – the crocodile-infested moat.