Fort William , India Fort William is a fort built in Calcutta on the Eastern banks of the River Hooghly , the major distributary of the River Ganges , during the early years of the Bengal Presidency of British India . It was named after King William III of England and Ireland and II of Scotland . In front of the Fort is the Maidan , which used to be a part of the Fort and is the largest urban park in Calcutta . History . There are actually two Forts William , the old and the new . The original was built in 1696 by the British East India Company under the supervision of John Goldsborough . Sir Charles Eyre started construction near the bank of the River Hooghly with the South - East Bastion and the adjacent walls . It was named after King William III in 1700 . John Beard , his successor , added the North - East Bastion in 1701 , and in 1702 started the construction of the Government House ( Factory ) at the centre of the fort . Construction ended in 1706 . The original building had two stories and projecting wings . An internal guard room became the Black Hole of Calcutta . In 1756 , the Nawab of Bengal , Siraj Ud Daulah , attacked the Fort , temporarily conquered the city , and changed its name to Alinagar . This led the British to build a new fort in the Maidan . The rebuilding of the fort was started by Robert Clive in 1758 , after the Battle of Plassey ( 1757 ) , and completed in 1781 at a cost of approximately two million pounds . The area around the Fort was cleared , and the Maidan became " the Lungs of Kolkata " . It stretches for around 3 km in the north - south direction and is around 1 km wide . Fort William is one of Kolkata ' s most enduring Raj era edifice . This is a fort of stupendous dimensions and is spread over an area of 70 . 9 hectares . It was built by Robert Clive in the year 1781 . Fort William has the dubious distinction of being the only fort in the world from which not a single shot was fired . Today this fort located in the periphery of the lush green Maidan is the property of Indian Army . The headquarters of Eastern Command is based at Fort William and it has provisions for accommodating 10 , 000 army personnel . Much of Fort William is unchanged except for the fact that the St . Peter ' s Church which used to serve as a chaplaincy center for the British citizens of Kolkata is now a library for the troops of HQ Eastern Command . For the welfare and relaxation of the 10 , 000 odd military personnel who are residents of Fort William , the army has provided every kind of facilities within the Fort premises like the emerald blue swimming pool , cinema hall , shopping mall , laundry , outdoor playground , restaurants and even a post office . This colossal fort was built out of fear by the British East India Company . The British felt vulnerable after their defeat at the hands of Siraj - Ud - Daula in the year 1756 and the British East India Company for the first time in many years were showing signs of wear and tear . The Old Fort was repaired and used as a customs house from 1766 onwards . The New Fort is still in use as the headquarter s of the Eastern Command of the Indian Army . The Army guards it heavily , and civilian entry is restricted . Structure . The Fort is built of brick and mortar in the shape of an irregular octagon with an area 5 km² . Five of its sides face landward , and three towards the Hooghly River . The design is that of a star fort , suited to defence against cannon , but from before the advent of explosive shells . It is surrounded by a dry moat 9 m deep and 15 m broad , which can be flooded but is designed as an area in which to use enfilade ( or " flanking " ) fire against any attackers reaching the walls . There are six gates : Chowringhee , Plassey Calcutta , Water Gate St Georges and the Treasury Gate . There are similar forts at places like Thalassery in Kerala . It has 9 - hole golf course .