Circus, in ancient Rome, was a large oblong building adapted for chariot-races and horse-races, and used also for the exhibition of athletic exercises, mock-contests, and conflicts of wild beasts. The Circensian Games were alleged by tradition to have originated in the time of Romulus; and Tarquinius Priscus celebrated a notable victory by games. The games continued to be held annually, and a permanent edifice was soon afterwards constructed. This was distinguished, subsequent to the erection of the Flaminian and other large circi, as the Circus Maximus. It must have been altered and enlarged at various times. Dionysius says it could hold 150,000 persons; Pliny, 260,000; and P. Victor, 385,000. Its extent also has been variously estimated. In the time of Julius Cæsar it was three stadia or 1875 feet long, and one stadium or 625 feet wide, while the depth of the buildings surrounding the open space was half a stadium, or about 312 feet. The plan was oblong, rounded at one end and square at the other. Along the sides and at the curved end were ascending ranges of stone seats for the spectators. At the other end were the carceres or stalls in which the horses and chariots were kept, until, on a given signal, the gates were simultaneously flung open. In the centre was the spina, a long and broad wall round which the charioteers drove, terminating at both ends at the meta or goals—conical pillars which marked the turnings of the course. Julius Cæsar made an curripus or canal round the course to protect the spectators more effectually during the conflicts of wild beasts.
The circus was especially adapted for chariot-races, an amusement of which the Romans were passionately fond. The length of a race was seven circuits round the spina, and twenty-five races were run in each day. The number of chariots was usually four. The athletic exercises, such as boxing and wrestling, sometimes terminated fatally. A regular battle was sometimes represented (Pugna Equestris et Pedestris). By the formation of canals and the introduction of vessels, a Naumachia, or sea-fight, was occasionally exhibited; but, under the empire, this species of exhibition, as well as the Venatio, was gradually transferred to the Amphitheatre (q.v.). Animals for the Venatio or hunting were procured from every available part of the Roman empire, including Africa and Asia. The exhibition not only afforded an opportunity for the display of private munificence or ostentation, but attained the importance of a political engine, which none who aspired to popularity could afford to overlook. The turbulent classes often demanded doles of bread and circus games (panem et circenses) from candidates. When Pompey opened his new theatre he is said to have given public exhibitions in the circus for five days, during which five hundred lions and twenty elephants were destroyed. The Greek hippodrome was very similar in its arrangements to the Roman circus.
In modern times the circus survives but as the shadow of a name. It is about the same size as the modern theatre, and is employed principally for the exhibition of feats of horsemanship and for acrobatic displays. Modern circuses are of two kinds—those that hold performances in permanent buildings, of which there are only a comparatively small number in Britain and the United States, and those that 'tent' or occupy temporary erections in spring and summer, and return to buildings in winter. A circus manager on a tour must have a plentiful supply of novelties in the shape of graceful and daring riders, conjurers, and performing horses. A stud of highly trained performing horses, often of great value, is an important feature in every well-appointed circuses. English and American equestrians are superior to those of any other nationality, and their services are eagerly sought for on the Continent, where the bulk of the performers are English. Astley (q.v.) was the most famous of English circus-managers. The Paris hippodrome is celebrated. But the circus in connection with Barnum (q.v.) and Bailey's 'Greatest Show on Earth' is probably the most important ever organised, including a whole army of performers, 'mid-air artists,' and male and female equestrians.