CaerleonArticle Free Pass Caerleon, Welsh Caerllion, town,
archaeological site, and residential suburb of Newport, Newport
county borough, historic county of Monmouthshire (Sir Fynwy),
Wales, on the River Usk. It was important as the Roman fortress
of Isca Silurum, which was, with Deva (Chester) and Eboracum
(York), one of the permanent legionary bases in Britain. The
foundation of the fortress, set on a terrace in a wide bend of
the Usk, is dated to 74–75 ce, when the conquest of the Silures
of southeastern Wales began. The headquarters were built about
75 and the baths about 85, and the latest known structural work
took place in 253–255. Toward the end of the 3rd century, the
legion may have been removed and split up into smaller units.
The fortress was occupied, probably by a nonmilitary population,
until the 370s. Caerleon, traditionally a seat of the legendary
King Arthur, was a Welsh princely capital until the Norman
Conquest (1066) and thereafter was a marcher lordship (border
district) mainly in Welsh