The fort was shaped rather like a playing card with defences of earth and timber, symmetrically placed gates and streets of timber-framed buildings.

Still clearly visible after nearly two thousand years are the remains of a shrine, a strongroom for the pay-chest and the basilica where the commanding officer would issue orders and hold courts martial.

This is no thanks to the medieval builders who plundered stone from Segontium to help create Edward I’s magnificent castle at Caernarfon half-a-mile away.

The fort was surrounded by a settlement, or vicus, full of camp followers, traders and eventually the families of soldiers. Out here you can find traces of the garrison bathhouse, a mansio (guest house) and a temple to the god Mithras.