Secunderabad, also spelled as Sikandarabad (, ), is a twin city of Hyderabad and one of the six zones of the Greater Hyderabad Municipal Corporation (GHMC) in the Indian state of Telangana. It is the headquarters of the South Central Railway zone. Named after the Mir Akbar Ali Khan Sikander Jah, Asaf Jah III, Nizam of the Asaf Jahi dynasty, Secunderabad was established in 1806 as a British cantonment. Although both the cities are together referred to as the twin cities, Hyderabad and Secunderabad have different histories and cultures, with Secunderabad having developed directly under British rule until 1948, and Hyderabad as the capital of the Nizams' princely state of Hyderabad. Geographically divided from Hyderabad by the Hussain Sagar lake, Secunderabad is no longer a separate municipal unit and has become part of Hyderabad's Greater Hyderabad Municipal Corporation. Both cities are collectively known as Hyderabad and together form the sixth-largest metropolis in India. Being one of the largest cantonments in India, Secunderabad has a large presence of army and air force personnel. History Following the dissolution of the Chalukya empire into four parts in the 11th century, the areas around the present day Hyderabad and Secunderabad came under the control of the Kakatiya dynasty (1158–1310), whose seat of power was at Warangal, northeast of modern Hyderabad. In 1310 the area of present day Hyderabad and Secunderabad came under the rule of the Delhi Sultanate after the capture of Warangal, the Kakatiya capital. The modern city of Hyderabad was built and founded in 1592 by the Golconda Sultanate under Muhammad Quli Qutb Shah. The modern Secunderabad is also the site where the then Mughal emperor Ahmad Shah Bahadur was defeated in the year 1754 by the Maratha Empire; the emperor arrived after the death of Nawab Anwaruddin Khan nearby at the Battle of Ambur in 1749. Anwaruddin Khan was the Nawab of Arcot. The area around Secunderbad changed hands between various rulers, and the area was part of Nizam's Hyderabad by the 18th century. Modern Secunderabad was founded as a British cantonment after Nizam Asaf Jah II was defeated by the British East India Company. He was then forced to sign the 1798 Treaty of Subsidiary Alliance to get the favor of British troops camped in the village of Ulwul, north-east of Hussain Sagar, the lake that separates Secunderabad from its twin city Hyderabad. In 1803, Nizam Sikandar Jah, the third