Well preserved Roman fort discovered on Channel Islands

This summer saw excavations on the island of Alderney to investigate what was traditionally believed to have been a Roman structure – with surprising results.

Local tradition has indeed suggested that the site was Roman, but until recently any investigations had proved inconclusive. The site, known as the Nunnery, has had various uses over time including military works, a farm, the residence of the island's governor and holiday homes.  In 2008 Guernsey Museums and the Alderney Society joined forces to investigate and excavate and have managed to prove that the Nunnery is actually an extremely well-preserved Roman military structure.

The 2008 excavation put a trench against the outer face of the north wall of the structure. Whilst only two fragments of tile and 11 small Roman sherds were found the trench did show that the fort wall continued for almost 2m below the modern surface, giving the rampart a height of 6.8m. The foundations were made up of a layer of beach stones in mortar and built directly on sand. It may have been that the foundations were built on timber piles, a common Roman technique.

 In 2009 attention turned to a wall that was thought to be ‘new’, that is, a later addition thought to have been built to replace the collapsed east rampart. The ‘new’ wall did not seem to make sense militarily, and some scholars had previously observed that its outer face looked older than the fort it was repairing. When the overgrown ivy was stripped from the ‘new’ east wall it revealed a double tile-bonding course with two buttresses and running for 17m. It was a Roman wall. This proved there was a Roman building inside the Nunnery and the excavators began to suspect that it was a tower since all northern English Roman forts have a tower in the middle.
In 2010 the excavators went back to try and find the tower - and found it. Dr Monaghan of Guernsey Museums said, "The walls are 2.8m (9ft) thick, we don't know how high it was, but it would have been a very big structure - it's as thick as Hadrian's Wall." The tower was around 18 sq m.

Old postcard showing 'The Nunnery'
The fort is in an extremely good state of preservation: "It's in a better state than what they call the Saxon shore forts off southern England, it's in better nick than most of Hadrian's Wall” said Dr. Monaghan.  

As with the Saxon shore forts, this was build to guard the shore, in this case the entrance to Longis Bay, Alderney's only natural harbour. The fort is also placed to control the sea between the island and the French coast, some 8 miles away. It dates to the late 4th century, a period of anxiety for the Romans that led to the construction of these forts in various locations.

The extent of the Roman presence on the island of Alderney is still not well understood. There is some sparse evidence for Roman settlement on Alderney but it is known from literary sources that the Channel Islands were visited by Roman officials and traders. The traditional Latin name of the island is Riduna though the exact etymology of the Island's name is obscure.