Portus Adurni is the best-preserved Roman fort north of the Alps. It was established in the 3rd century CE and is situated in Portsmouth (England).
The fort was part of the fortification system (the so-called “Saxon Bank”) of southern Britain. The fort covered an area of 36,000 square meters; it had external walls 6 m high, 3 m thick and 200 m long. The structure was made of flint bound with limestone slabs.
The main purpose of the fort was to secure the region, control the trade and transport of goods by sea, and defend Britain against raids through the English Channel. This fortress also played an important role during the rebellion of Carausius in Britain in 285 CE.
