Nanstallon in 1965 by Aileen Fox and Professor W. L. D. 'Bill' Ravenhill. Until recently (2007) it was the second Roman fort in Cornwall but following a geophysical survey another Roman fort has been found away near Restormel Castle. Constructed c. AD 55–60, Nanstallon fort is situated in mid Cornwall near the Fowey-Camel trade and communication route. Nanstallon was probably a forward operating base and was strategically well-placed for a Roman presence to be felt. However, the Roman Legion at Exeter was withdrawn c. AD 75 and with no Roman town west of Isca Dumnoniorum Cornwall settled down to four centuries
Isca Augusta and timber ramparts of the fortress were strengthened by the addition of a stone revetment at the front. This "composite" rampart consisted of a stone wall 5 to 5½ feet thick, backed by a clay bank and fronted by a single ditch By 120 AD, detachments or vexillations of the legion were needed elsewhere in the province and Isca became more of a military base than a garrison. However, it is thought that each cohort still maintained a presence at the fortress. When Septimius Severus seized power in the 190s, he had Isca refurbished and the legion were in residence