Agra is located about 139 miles southeast of Delhi along the west bank of the River Jumna. Located between Mathura and Surajpur, and referred to by Greek historians as Methoras and Cleisobora, Agra was part of the Surasena Empire, with Mathura as the capital. Geographically, Agra is centrally located in northern India, imbuing it with political and commercial strategic advantage. Many battles have been fought for control of the city, and it became the capital city during the sixteenth and seventeenth centuries. The fortified core composed by the Agra Fort originally served the Rajputs, as an impregnable, protective, screen against invasions. It finally fell in 1081 to Mahmud Shah, the governor of the northwest regions and the Punjab. Jaipal, then the Rajput ruler, defended the fort valiantly but surrendered to the Ghaznavid army when reinforcements failed to arrive. Though Agra was sacked and owed its allegiance to Ghazni, the Rajput rulers still effectively controlled it. It was during the Second Battle of Tarain (1192) that the Ghaznavids led by Muhammad bin Sam established their rule. 

Following the Ghaznavids, the establishment of the Delhi Sultanate was marked by an asserted allegiance to Delhi. Intermittent revolts and a revived Rajput presence in Agra that took control of most of the region soon became a threat. Agra came under the direct control of Sikandar Lodi in 1492 after the governor of Agra, Haibat Khan, rebelled against Delhi. Given the central location of the city, Sikandar shifted the capital to Agra in 1504. Under Sikandar Lodi, Agra was endowed with cultural and artistic aspects, looking to be viewed as the Shiraz of India. With the death of Ibrahim Lodi at Panipat in 1526, and the establishment of the Mughal Empire, Agra retained its stately status. During the reign of Sher Shah Sur, Agra became the node from where the road networks began and connected the extent of the Sur Empire. 

During the Mughal Emperor Akbar's reign, Agra came to be known as 'Akbarabad'. It flourished under his patronage, and his successors Jahangir and Shah Jahan. The city is today famous for its many architectural trophies, dated to the Mughal period. The present day Agra Fort was built by Akbar in 1565, along with the new capital at Fatehpur Sikri, along the outskirts of Agra, which was eventually abandoned. The Taj Mahal was the contribution of Shah Jahan to the cityscape. Agra's significance as a political centre ended when Shah Jahan moved the capital to Delhi in 1638. 

In 1761, the Jats under the Raja of Bharatpur sacked Agra. It was then taken by the Maratha dynasty in 1770. The British gained control of the city after the Second Maratha War in 1803. It was besieged during the rebellion against the British in 1857. Post-independence Agra is one of India's major industrial cities and has a thriving tourist economy. 

Sources: 

Davies, Philip. The Penguin Guide to the Monuments of India - Volume 2: Islamic, Rajput, European. London: The Penguin Group, 1989.

Nath, R. Agra and its Monuments. Agra: The Historical Research Documentation Programme, 1997.

Sanwal, B.D. Agra and its Monuments. New Delhi: Orient Longmans Limited, 1968.

DK Eyewitness Travel Guide: India. London: Dorling Kindersley Limited, 2002.