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
Norwich redevelopment. On 23 November 1981, a minor F0/T1 tornado struck Norwich as part of the record-breaking nationwide tornado outbreak on that day, causing minor damage in Norwich city centre and surrounding suburbs. Norwich has been governed by two tiers of local government since the implementation of the Local Government Act 1972. The upper tier is Norfolk County Council, which manages strategic services such as schools, social services and libraries across the county of Norfolk. The lower tier is Norwich City Council, which manages local services such as housing, planning, leisure and tourism. Norwich elects 13 county councillors to the 84-member