Map - Secunderabad

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.

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, 148 km 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 Nizam of Hyderabad, changed Ulwul's name to Secunderabad after himself. The city was formed in 1806, after the order was signed by the Nizam allotting the land north of Hussain Sagar to set up the British Cantonment.

The twin cities are separated by the man-made Hussain Sagar lake, which was built during the reign of the Qutb Shahi dynasty in the 16th century. Unlike Hyderabad, the official language of Secunderabad was English. Secunderabad was exempted from customs duty on imported goods, thus making trade very profitable. Various new markets such as Regimental Bazaar and General Bazaar were created. After the First War of Indian Independence of 1857, the construction of a 7 m wall was started at Trimulgherry and completed in 1867.

Secunderabad Junction railway station, one of the largest in India and the zonal headquarters of South Central Railway, was established in 1874. The King Edward Memorial Hospital, now known as Gandhi Hospital, was established in 1851. A civil jail (now a heritage building known as Old Jail complex near Monda Market) was also established. Originally constructed in 1860 as the country house of the British Resident at Hyderabad, the Residency House is now known as the Rashtrapati Nilayam, the official retreat of the President of India.

Sir Winston Churchill, the prime minister of the United Kingdom during World War II, was posted in Secunderabad during the 1890s as a subaltern in the British Army. Sir Ronald Ross conducted his initial research on the cause of malaria in the city of Secunderabad. The original building is today called the Sir Ronald Ross Institute and is located on Minister Road.

Secunderabad Municipality was first formed in 1945. Later in 1950, along with Hyderabad Municipality, it was upgraded to Secunderabad Municipal Corporation under the Hyderabad Corporation Act, 1950. In 1960, by the Hyderabad Municipal Corporation Act of 1955, Secunderabad Municipal Corporation was merged with Hyderabad Corporation to form a single municipal corporation. Today Secunderabad is part of the Hyderabad district.