Caerleon is a town and community in Newport, Wales. Situated on the River Usk, it lies 5 miles (8 km) northeast of Newport city centre, and 5.5 miles (9 km) southeast of Cwmbran. Caerleon is of archaeological importance, being the site of a notable Roman legionary fortress, Isca Augusta, and an Iron Age hillfort. Close to the remains of Isca Augusta are the National Roman Legion Museum and the Roman Baths Museum. The town also has strong historical and literary associations: Geoffrey of Monmouth elevated the significance of Caerleon as a major centre of British history in his Historia Regum Britanniae, and Alfred Lord Tennyson wrote Idylls of the King (1859–1885) while staying in Caerleon.

The River Usk rises on the northern slopes of the Black Mountain, Wales, in the westernmost part of the Brecon Beacons National Park. Initially forming the boundary between Carmarthenshire and Powys, it flows north into Usk Reservoir, then east by Sennybridge to Brecon before turning southeast to flow by Talybont-on-Usk, Crickhowell and Abergavenny, after which it takes a more southerly course.