A tiny vestige of the huge horse-shoe shaped, 450 yard long, arena built primarily for the sport of chariot racing - yes, Charlton Heston, Ben Hur was all true! - can be seen when you walk to the Musée départmental Arles Antiques The obelisk that is currently in the centre of the Place de la République is said to be the one that was traditionally was placed in the centre of the circus, half way along its length.  Intended to house more than 20,000 spectators, it was built on marshy land on a foundation of more than 40,000 wooden piles driven into the mud.  Nice model in the neighbouring museum.