A previously unknown Roman amphitheatre has been unearthed in the Rheinfelden district in the canton of Aargau, near Switzerland’s border with France and Germany.
The discovery was made in Kaiseraugst, a municipality named after the Roman town of Augusta Raurica, which was founded here in 44 BC. Aargau Cantonal Archaeology were carrying out excavations to the west of the Roman town’s fort, the Castrum Rauracense, in advance of the construction of a new boathouse on a site known to have been the location of a Roman quarry, but archaeologists were surprised to encounter the remains of a large stone structure here as well.
The building appears to be c.50m long and 40m wide, with an oval ring of limestone walls, large entrance gates of sandstone, and the imprints of a wooden post where the tribune once stood, all of which indicates that the structure was an amphitheatre where venationes (animal hunts) and other popular forms of entertainment were held.
This is the third amphitheatre discovered in Augusta Raurica, bringing the total known in Switzerland to eight, but the Kaiseraugst example is particularly interesting because it appears to have been built unusually late. The amphitheatre was constructed in the valley of the Roman quarry, indicating that it must have been built after the quarry’s abandonment in late Antiquity. This is supported by the building materials used in its construction – stone blocks and mortar resembling those used in the fort walls of the late Roman Castrum Rauracense nearby, which was built c.AD 300 – as well as the discovery of a coin dated to between AD 337 and 341. All of this suggests that the amphitheatre was constructed in the 4th century AD, making it potentially the youngest amphitheatre known in the Roman Empire.
The boathouse construction project has been adapted so that the Kaiseraugst amphitheatre can remain in situ and will be protected for the future.