The early Kentish monastery of St Martin was probably founded within the old Roman Saxon-Shore Fort at the end of the seventh century. Destroyed by Viking raids in the late ninth century, it is thought that the Canons of St Martins moved to a new church built within the Anglo-Saxon settlement on Castle Hill above the town. This church later became the church of St Mary-in-Castro, but before the Norman Conquest it was almost certainly the great church built for the canons of St Martins, whose many estates are mentioned on the first page of the Domesday Book. At the time of the Norman Conquest the Castle started to be built on the hilltop, and the canons had to find a new home in the town below.Building commenced around 1070 at a site on the western side of the present Market Square. Building work on the church seems to have stopped at the beginning of the twelfth century when the nave had only just been started. The canons of St Martins were subject only to the King and the Pope, and this was not to the liking of the Archbishop of Canterbury. In 1130 the King Henry I was finally persuaded to grant the church and all its estates to the Archbishop and the monks of Canterbury. The Archbishop originally planned to complete the church and use it for the new order, but the monks of Canterbury did not like this , and in 1139 they managed to persuade him to build a new house just outside Dover which became St Martins Priory.The church, later called St Martin-le-Grand, was eventually completed to form a large parish church. By the late middle ages, this church apparently combined under one roof three parish churches, St Martin, St Nicholas and St John the Baptist. Within the church itself there were a whole mass of altars and chapels which are mentioned in various later fifteenth and early sixteenth century wills.By 1536 St Martin-le-Grand was in very poor condition, and when the Reformation came a few years later it ceased to be used for its parish churches. The altars were removed in 1546, and the eastern part was let by the Corporation for shops and tenements fronting onto the Market Square. A passageway ran through the central apse to the enlarged graveyard in the western part of the church. This graveyard was still in use until the late nineteenth century, and large fragments of the eastern part of the church were still incorporated into houses at this time. Until the Second World War the building line still bulged out into the Market Square in line with the old church building. The area was badly damaged in the Second World War and subsequent excavations have helped to determine the plan of the church. Some remains of the church can be seen just off the Market Square behind Barclays Bank.