Imagine: It’s the year 100 CE, you’re a Roman soldier stationed in what is today south Wales, and you’re in search of an evening’s entertainment. You’d have probably gone to the amphitheater in the Isca Augusta fortress, which is now a well-preserved window into Roman culture.

Over the centuries, long after the Romans were gone, the amphitheater gained notoriety for an entirely different reason. The belief took root that it was also the site of King Arthur’s famous Round Table.

The King Arthur association is thanks to the early historian Geoffrey of Monmouth, who after visiting Wales in the late 12th century, wrote of the spot as King Arthur’s court. His reports are easily contested in the absence of other evidence, but their influence reached far and wide. In 1405, an invading French force even visited the site because of its association with the fabled king. Naturally, the National Museum of Wales milked this myth as it tried to raise funds for excavations around the Caerleon area in 1926.

In reality, the amphitheater was built around the year 90 CE outside fortress walls that went up around 74 CE. It is a testament to expanding Roman control, and the events that took place at the site—animal hunts, gladiator battles, military parades—glorified that aggressive spirit. There’s no doubting how popular these kinds of exhibitions were. Over 6,000 spectators could fill the seats, more people than were serving in the second Roman legion occupying the area.