"The circus building itself was based on the Greek hippodrome. The circus had seats for spectators around a "u" shaped arena. The racing took place in the arena around a barrier (spina) in the middle, with turning posts (metae) around each end. At one end of the arena were the starting gates. The first circus built in Rome was the Circus Maximus that was constructed during the monarchy. It was built completely from wood. Later it was rebuilt at various times. The final version could seat 250,000 people, it was built of stone and measured 400 m in length and 90 m in width."