The Roman villa at Great Witcombe, built in the mid third century and occupied until the fifth century, is a fantastic site on the on the western edge of the Cotswolds. Originally excavated in the early nineteenth century, the terraced nature of the construction of the villa is still both clear and attractive. The mosaics are protected and can only been seen occasionally - the link at the head of this post has a picture. The most recent write up is Neil Holbrook, "Great Witcombe Roman Villa, Gloucestershire: field surveys of its fabric and environs, 1999-2000," Transactions of the Bristol and Gloucestershire Archaeological Society 121 (2003) pp. 179-200. The pdf can be read here.
The temple room
Overview of the site
Large barn-shaped structure on the lower level