Forts in India The capital of each raja or chieftain was a fort around which a township grew and developed ; this pattern can be seen in many South Asian cities such as Delhi , Agra , Rajasthan , Lahore , Pune , Calcutta and Mumbai . Two forts in India are UNESCO world heritage sites the Agra fort and the Red fort . The oldest surviving fort in India is the Qila Mubarak at Bathinda which had it origins in 100 AD during the Kushan empire , The Kangra Fort in Kangra believed to have been built by the still surviving Katoch dynasty after the battle of Mahabharta . The fort was written about by the scribes of Alexander the Great , thus making it the oldest fort in India . Medieval Delhi developed around Chandni Chowk , the township adjoining the Red Fort while and Kolkata came about around Fort William built by the British . Many small towns ranging from Jhansi to Chandragiri grew around forts . Some towns even acquired the names from the forts . Durg is fort in Hindi . Satara was so named because of the seventeen walls of the fort . Then there are famous monuments in certain cities and towns that overshadow the importance of the forts . Agra Fort pales into comparative insignificance against the glory of the Taj Mahal . Khajuraho temples overshadow Rajgarh Fort . The conquest of , or battles for the forts of India have been significant occasions in Indian history . The capture of Qila Mubarak ( Bathinda ) in 1004 AD by Mahmud of Ghazni heralded the advent of Islamic rule in India . The struggle of Shivaji against the Mughals in the seventeenth century and his reign occur against the backdrop of forts in the Deccan . The capture of Seringapatam and death of Tippu Sultan in 1799 cemented British rule in South India . The capture of Gawilghur by Arthur Wellesley , later Duke of Wellington , ended the Maratha threat to British rule in Central India at the time of the Second Anglo - Maratha War . The flag of independent India was first unfurled from the ramparts of the Red Fort by none other than Jawahar Lal Nehru , first Prime Minister of India on the morning of 15 August 1947 . This practice of unfurling of flag followed by a speech by the Prime Minister continues each year on Independence Day . Just after World War II , the Red Fort had been the scene of the famous trial of the Indian National Army . Etymology . Most of the forts in India are actually castle s or fortress es . But when the British Government in India were cataloging them in the 17th – 19th century they used the word forts as it was common in Britain then . All fortifications whether European or Indian were termed forts . Thereafter this became the common usage in India . In local languages the fort names are suffixed by local word for fort thus usage of the Sanskrit word " durga " , or Hindi word " qila " or the word " garh " or " gad " in Rajasthan , Assam and Maharashtra is common . For example , Suvarnadurg , Mehrangarh , Sudhagad etc . Forts in ancient India . Three major methods were used for the construction of ancient Indian forts . The first consisted of earthen ramparts . Often they were constructed of the sand which was dug out of the ditch surrounding the fort . The second of rubble with earth on the outside which was more sturdy . The third type of construction was with stone and masonry work . The last was the strongest . Often materials from demolished forts were reused in the building of new forts . By 4 BCE , fortified cities were common in India . The largest ones were between the city of Mathura ( on the Yamuna river ) and Magadha ( on the Ganges ) . Another series of forts in the south , was on the Ujjain ( on the Narmada ) leading into the Deccan . These are inferred by the remains of fort walls and bastions seen on excavation at Rajagriha and at several sites in the Gangetic plain notably Kaushambi . At the latter site huge walls of burnt brick , which look like they have been battered . There does not seem to be any formal planning of these forts . There are few descriptions of these ancient structures . The most noted is the one by Megasthenes , an ambasaddor of Seleucus I Nicator to the court of Chandragupta Maurya . He describes Patliputra as being guarded by a ditch with wooden walls . The fort had 570 towers and 54 gates with colonnaded halls decorated with gold and silver . One such hall has been excavated and is one of the oldest stone structures in India . Types of Ancient Indian Forts . Though most of the structures have been decayed and are lost , India ' s legacy of ancient forts is seen mostly in the shastras ( ancient Indian treatises ) and in the reliefs on stupas . On some of the early relief work , the carvings indicate that ancient Indian forts has crenallations , embrasures and sloping walls . The Arthashastra the Indian treatise on military strategy describes six major types of forts differentiated by their major mode of defense . Each type of fortress had different advantages . Manu ( author of the Manusmṛti a Vedic text ) considered the hill forts offers the best defenses . Some Sanskrit text also consider hill forts to be the abode of gods and hence auspicious . Manu also considers the disadvantages of other fortresses . A fortress surrounded by water often sheltered reptiles and snakes , which made for a rapid spread of disease ; on the other hand , reptiles and snakes could deter an assault on a fortress , and disease could force the enemy to lift a siege . Earth fortresses often swarmed with rats and rodents , which might in the long run eat away their foundations . Monkeys plagued the inhabitants of arboreal fortresses , while a fortress that housed a lot of people had to be kept well supplied with food and water to feed all those mouths . However the Mahabharata considers Nri - durga to be the best defensive structures . Most of the time a combination of defenses were used to guard the fort . Ranthambhore Castle , for example , stands on a hill ( " giri - durga " ) and used to be surrounded by dense forests ( " vana - durga " ) . When a considerable garrison of soldiers was billeted in it , the castle could also be classified as " nri - durga " . The method of planning of the fort is also described along with the layout of the roads . Kautilya suggests that the roads should be laid along the four cardinal directions with a temple at the centre . The Kings house should be at the north . One of the oldest and most well preserved of such structures are the excavated ruins of ancient fortifications at Sisupalgarh in Orissa . It is estimated to date from the 3rd century BCE and was in occupation for a thousand years at least . Outlines of the fort indicate it had eight gates and thick walls . The western gate was quite elaborate . In 2005 , sonar analyais suggested the presence of a deep moat around the fort . Forts in Medieval India . With the advent of the Muslims , closely followed by the introduction of artillery in the 16th century there were several changes to the construction and design of forts . These changes were similar to the changes that took place in Western forts with the advent of gunpowder , i . e . the lowering of walls , thickening of walls , further pushing out of bastions etc . The construction of a citadel in the centre and putting in more area between the citadel and the walls was characteristic of Muslim forts ( influenced in turn by the Norman motte and bailey ) . Classic examples of such structures are the Golkonda and the Berar fort . The gates of medieval Indian forts were highly decorated . Two distinct styles are seen . The Hindu style with a lintel and the Mughal style with an arch . Gates in Indian forts were often high and wide to allow elephants to pass . Often they had rows of sharp , stout iron spikes to dissuade the breaking down of the gate by the elephants of an invading army . Such a gate with spikes can be seen on the Shaniwarwada fort , Pune . The walls of the forts were often looked higher from the outside than the inside as the forts made use of the natural rock formations on hills . This not only gave an illustion of greater height but also lead to the lower walls of the fort to be entirely made up of natural rock providing almost a perfect defense against the use of a battering ram or elephants to tear down the walls . Construction . Stone was the main material for building fortifications in medieval India . Walls were erected by one of the following three construction methods . A wall could be an earthen rampart faced with stone on both sides . The rampart was built using the earth excavated while digging the ditch , with three - quarters of it used for building a rampart and one - quarter for levelling out the surface inside the fortress and in front of the ditch . Facing the rampart with stone allowed for the erection of higher and steeper walls than those possible with a purely earthen rampart . The structure had a substantial shortcoming , however : an earthen core accumulated water , which could destroy the stone shell . Drainage channels were therefore installed along the length of the wall from top to bottom . The second method consisted of filling the space between the outer layers with earth mixed with rubble . This core was considerably harder than simply using rammed earth . The third and most advanced method involved the use of mortar . A rubble - built wall fastened with mortar was strong and long lasting . Construction methods depended , however , on the materials available . In medieval India , several reports exist of the practice of burying humans either dead or alive in the foundations of fort walls , to ensure their stability , being widely followed . It was believed that the ghosts of those sacrificed as such would keep evil spirits away . During the building of the Sri Qila , Delhi Alauddin Khilji is reported to have buried 8 , 000 skulls of Mughals killed by him into the foundation . During the building of Purandar Fort one its bastions gave way several times . The king of Berar then ordered his minister an Esaji Naik Chive to bury a first - born son and his wife into the foundation of the bastion . This was promptly done and after a further offering of gold and bricks . When the bastion was finished Esaji Naik was given possession of the fort and the father of the sacrificed boy was rewarded with two villages . This custom was also followed by Shivaji when he built his forts . Many Indian fortifications have parapets with peculiarly shaped merlon s and complicated systems of loopholes , which differ substantially from similar structures in other countries . Typical Indian merlons were semicircular and pointed at the top , although they were sometimes fake : the parapet may be solid and the merlons shown in relief on the outside ( as at Chittorgarh ) . What was unique is the arrangement and direction of loopholes . Loopholes were made both in the merlons themselves , and under the crenels . They could either look forward ( to command distant approaches ) or downward ( to command the foot of the wall ) . Sometimes a merion was pierced with two or three loopholes , but more often , one loophole was divided into two or three slits by horizontal or vertical partitions . The shape of loopholes , as well as the shape of merlons , need not have been the same everywhere in the castle , as shown by Kumbhalgarh . Forts constructed by the British . With the advent of the East India Company , the British established trading posts along the coast . The need for security against local rajas as well as other European rival nations led to the construction of forts at each post . Mumbai fort , Fort William in Kolkata , Fort St George in Chennai were the main bastions constructed . These cities developed from the small townships outside the forts . Parsimony of the East India Company , non - availability of trained engineers and use of local materials and artisans resulted in the simple design and construction initially . The vulnerability of these earlier forts , hostilities with the French and the growing might of the Company resulted in stronger and more complex designs for the second round of construction , the design of Fort St George reflecting the influences of the French engineer Vauban . State of castles today . Although no Indian forts were destroyed by sudden disasters , there are several which were abandoned due to the ambitions of their rulers and have consequently deteriorated over time . Very few castles have survived unchanged since the early Middle Ages or even since the 14th - 15th centuries : most of those built in the 10th - 15th centuries were later rebuilt and altered . Castles were still used as living quarters until the 19th - 20th centuries , and so were continually modified . Even now , some of them are private property .