Many mediaeval market towns in Suffolk were also places of political power and military importance. Clare is important because the junction of the Chilton stream and the river Stour created an ideal defensive site. An early earth Fort, Clare Camp, was built at the northern end of the town on a spur of land overlooking what was then impassable marshes. The Mediaeval Castle was built at the junction of the two rivers on a specially built mound surrounded by marshes. The part of the curved walls can be seen in the picture. The town is built between the two sites on a river terrace just above the flat land of the flood-plain. Because of its castle and its position in the mediaeval wool trade region of Suffolk, an important market developed. This is just visible in this photograph.

The buildings that remain today are either shops or private houses. In an attempt to remain competitive during the Victorian period the river Stour was canalised at this point to provide water power for flour mills. A railway was also built. The station buildings and the large warehouses immediately next to the sidings (now a car park) were built on the flat marshland. Once drained this was ideal for building railways cheaply.