Among the Romans, a circus was a nearly rectangular building without a roof, in which public chariot-races and exhibitions of pugilism and wrestling, etc, took place. It was rectangular, except that one short side formed a half-circle; and on both sides, and on the semicircular end, were the seats of the spectators, rising gradually one above another, like steps. On the outside the circus was surrounded with colonnades, galleries, shops, and public places. The largest of these buildings in Rome was the Circus Maximus, capable, according to Pliny, of containing 260,000, and according to Aurelius Victor, 385,000 spectators. At present, however, but few vestiges of it remain, and the circus of Caracalla is in the best preservation. The games celebrated in these structures were known collectively by the name of ludi circenses, circensian games, or games of the circus, which under the emperors attained the greatest magnificence.
The principal games of the circus were the ludi Romani or magni (Roman or Great Games), which were celebrated from the 4th to the 14th of September, in honour of the great gods, so called. The passion of the common or poorer class of people for these shows appears from the cry with which they addressed their rulers - panem et circenses (bread and the games!). The festival was opened by a splendid procession, or pompa, in which the magistrates, senate, priests, augurs, vestal virgins, and athletes, took part, carrying with them the images of the great gods, the Sibylline books, and sometimes the spoils of war. On reaching the circus the procession went round once in a circle, the sacrifices were performed, the spectators took their places, and the games commenced. These were:
1. Races with horses and chariots, in which men of the highest rank engaged.
2. The gymnastic contests.
3. The Trojan games, prize contests on horseback, revived by Julius Caesar.
4. The combats with wild beasts, in which beasts fought with beasts or with men (criminals or volunteers).
5. Representations of naval engagements (naumachioe), for which purpose the circus could be laid under water.
The expense of these games was often immense. Pompey, in his second consulship, brought forward 500 lions at one combat of wild beasts, which, with eighteen elephants, were slain in five days.
The modern circus is a place where horses and wild animals are trained to perform antics, and where exhibitions of acrobats and various pageantries, including a large amount of buffoonery, are presented. Research Circus