Later dwellings at Culver Street and artifacts from the 7th and 8th centuries are seen as evidence that the shell of the Roman town was still in use into the Saxon period. The "History of the Britons" traditionally ascribed to Nennius includes a list of the 28 cities of Britain, including a Cair Colun that has been thought to indicate Colchester. Archaeology aside, Colchester first explicitly re-enters the "written" historical record again in the Anglo-Saxon Chronicle for 917, the year it was retaken from the Danes by a Saxon army led by King Edward the Elder, who "restored" the borough to English rule. The walls of the colonia have been retained, and many of the Medieval and Saxon buildings in Colchester, including the Castle, St Botolph's Priory, St John's Abbey, Greyfriars, Holy Trinity church and many of the Norman "stone houses" were built from the vast amounts of Roman debris left over in the town. Over 25,000 cubic metres of reused Roman tile and brick was used for the Castle alone. The quarrying of Roman rubble for building material reached a peak in the 12th and 13th Centuries.