These links are to the principal Roman sites in Britain. Many of the ruins in England are administered by English Heritage, a few, such as Chedworth, are National Trust properties. In Wales, most sites are maintained by Cadw: Welsh Historic Monuments. Admittedly, published illustrations, especially of mosaics, often are better, but the intention is to show what the first-time visitor is likely to see.
References: A Guide to the Roman Remains in Britain (1988) by Roger J. A. Wilson; Discovering Roman Britain (1993) edited by David E. Johnston; Caerleon Roman Fortress (1994) by Jeremy K. Knight (Welsh Historic Monuments); Caerleon-Isca: The Roman Legionary Museum (1987) by Richard J. Brewer; Hadrian's Wall (1996) by David J. Breeze (English Heritage); Caerwent Roman Town (1997) by Richard J. Brewer (Welsh Historic Monuments); Segontium Roman Fort (1995) by Jeffrey L. Davies (Welsh Historic Monuments); Housesteads Roman Fort (1989) by J. G. Crow (English Heritage); Aldborough Roman Town (1995) by Colin Dobinson (English Heritage); Lullingston Roman Villa (1991) by David S. Neal (English Heritage); Corbridge Roman Site (1989) by J. N. Dore (English Heritage); Chesters Roman Fort (1990) by J. S. Johnson (English Heritage); Pevensey Castle (1999) by John Goodall (English Heritage); Wroxeter Roman City (1999) by Roger White (English Heritage); Richborough and Reculver (1997) by J. S. Johnson (English Heritage); Vindolanda (1999) by Robin Birley (Vindolanda Trust); The Roman Theatre of Verulamium (n.d.) by Kathleen K. Kenyon and Sheppard S. Frere; Birdoswald Roman Fort (1995) by Cumbria County Council; The Roman Fort of Arbeia at South Shields (1996) by Tyne and Wear Museums; Chedworth Roman Villa (1998) by Roger Goodburn (National Trust); Roman Verulamium (2000) by St. Albans District Council; Chester (1994) by Peter Carrington (English Heritage); Roman Britain (1996) by John Watney (Pitkin Guides); Lives of the Later Caesars (1976) translated by Anthony Birley (Penguin Classics); Hadrian's Wall (1987) by David J. Breeze and Brian Dobson (Penguin). Additional illustrations have been taken from The Oxford History of Classical Art (1993) edited by John Boardman.