Norwich also records the site of an Anglo-Saxon church in Tombland, the site of the Saxon market place and the later Norman cathedral. Norwich continued to be a major centre for trade, the River Wensum being a convenient export route to the River Yare and Great Yarmouth, which served as the port for Norwich. Quern stones and other artefacts from Scandinavia and the Rhineland have been found during excavations in Norwich city centre. These date from the 11th century onwards. Norwich Castle was founded soon after the Norman Conquest. The Domesday Book records that 98 Saxon homes were demolished to make
Cow Tower, Norwich to maintain the urban defences; like other towers and gatehouses belonging to the city, however, by this period the Cow Tower was probably leased out to a merchant or craftsman when not in military use. In 1549, Robert Kett led an uprising in Norfolk; marching on Norwich, his army camped on the north-east side of the river, overlooking Cow Tower. Two rebel attacks were then made across the river into the Hospital meadows, in an attempt to take Bishop Bridge, which would have given them access to the city. Kett had brought artillery, which he turned on the Cow Tower,