Portus Adurni

Portus Adurni is a Roman fort in Portsmouth built with stone walls constructed along the harbor's edge. The structure displays a rectangular layout with defensive towers positioned at regular intervals along its perimeter.

This fort originated during the third century as part of a coastal defense network protecting southern Britain. It served as a military stronghold during Roman rule and was eventually abandoned when the empire withdrew from these shores.

The site takes its name from the Roman port facility that once stood here, and visitors can observe how the Romans organized their military strongholds through the surviving walls and tower remains. The fort's layout reflects the practical thinking behind their defensive strategy along this coastline.

The site sits on the waterfront and is accessible through paths that circle the fortification. Visitors should be prepared for uneven terrain and some areas may be closed off due to preservation efforts.

What sets this fort apart is that its outer walls and semicircular towers remain visible today, making it one of the best-preserved Roman military structures north of the Alps. This level of completeness allows visitors to grasp the original defensive design in a way that few other sites can offer.