The circuses in the Roman times were always elongated in shape, as you can see on this illustration. The one in the old Roman city of Tarraco, built in the 1st century, was used to organize horse and chariot races.
Pretty odd fact for the time, the circus was strangely built inside the murals. It is leaning against the forum that you just discovered at the previous point of interest.
The Tarraco circus measured 325 meters long and 115 meters wide. It is considered one of the best-preserved circuses of the West, even though serveral parts stayed buried until the 19th century.