Tarragona once possessed one of the most impressive circuses in the Roman world, and is still one of the best preserved outside Italy. Built in the 1st century BC, it was used to stage chariot races (think ‘Ben Hur’) and other similar entertainments.

Over the years, the walls have been incorporated into the street pattern of the mediaeval city, but at the southern end there are impressive remains to visit, which show the structure of the stage and the large vaults beneath. The remains were incorporated into the mediaeval walls, and include a mediaeval tower. But the highlights are the vaults themselves, which run for several blocks under the streets and houses above. The construction used one of the Romans’ greatest innovations – concrete – as well as large blocks of stone.

The adjacent tower-like structure is the Praetorium, a Roman-era tower that once housed the stairs that connected the lower city to the vast provincial forum (of which little now survives) by way of the circus, to which it is connected by means of underground passageways. It stands at one of the corners of the vast rectangle of the provincial forum square. In the 16th century, it was transformed into a palace for the Spanish monarchs, and was then used as a prison.