What of the Roman walled towns and what did the Saxons find when they invaded. The largest walled town was London with 330 acres within the walls, then Cirencester with 240 acres, St.Albans with 225 acres within the walls and Wroxeter with 200 acres behind walls. At the other extreme Gloucester only had 46 acres surrounded by defensive walls and Caerwent with 44, in between were towns such as Winchester with 138 and Canterbry with 130 acres. Population obviously depends on the density of occupation, as always people go where the work is. Silchester provides an open site within the walls, but we do not know the extent of the wooden buildings in ancient built-up areas, as new construction with deeper foundations meant for archaeologists that post-holes disappeared. However the amphitheatre at St.Albans had 2,700 seats as recorded by Tacitus.