Simon de Senlis is also thought to have built the medieval town walls, which enclosed about and had four main gates. Though demolished now, the circular pattern of the main roads surrounding the town centre marks the original position of the walls. de Senlis founded the Cluniac Priory of St Andrew's in the area of Semilong, and built The Church of the Holy Sepulchre – one of four remaining round churches in England – and All Hallows' Church on the current site of All Saints' Church. His son, Simon II de Senlis, built St Peter's Church on a site between a former Anglo-Saxon palace and Northampton Castle. Simon II de Senlis also founded Delapré Abbey – another Cluniac priory – which still stands today. Other priories in medieval Northampton include St James' Abbey, Graye Friers, Blackfriars and Whitefriars. St. John's, a medieval hospital, was situated east of Bridge Street. A network of medieval tunnels remains under the centre of Northampton around All Saints' Church and the Market Square but their purpose, extent and significance have been disputed.
simon de senlis is also thought to have built the medieval town walls which enclosed about and had four main gates though demolished now the circular pattern of the main roads surrounding the town centre marks the original position of the walls de senlis founded the cluniac priory of st andrew's in the area of semilong and built the church of the holy sepulchre – one of four remaining round churches in england – and all hallows' church on the current site of all saints' church his son simon ii de senlis built st peter's church on a site between a former anglo-saxon palace and northampton castle simon ii de senlis also founded delapré abbey – another cluniac priory – which still stands today other priories in medieval northampton include st james' abbey graye friers blackfriars and whitefriars st john's a medieval hospital was situated east of bridge street a network of medieval tunnels remains under the centre of northampton around all saints' church and the market square but their purpose extent and significance have been disputed