The ancient Romans had a circus, but it wasn't anything like our modern circus. The ancient Roman circus was a place to stage elaborate "sporting" events. When it first began, the circus displayed Roman soldiers demonstrating their fighting skills against one another. Things got considerably nastier as time went by as the Romans indulged their taste for blood. The circus became a staging ground for fights to the death, with people and animals killing one another indiscriminately for the pleasure of the crowd. (Quite a crowd, by the way. The Circus Maximus in Rome, which was built around 600 B.C., allegedly seated up to 250,000 people at a time, although examining its ruins shows that a mere 150,000 could ever actually have been seated there.)

As the Roman Empire declined, so did these vast spectacles. The Roman circus disappeared completely during the Dark Ages.

The modern circus was invented by Philip Astley in 1768. He wanted to set up a riding school, but he had no funds to get it going. To raise money, Astley decided to charge admission to a trick riding show.

The problem with trick riding shows in those days was that they were set up as a long, straight track. The audience would sit near the middle of the track. The audience would see one trick as the horses dashed past, then they would have to wait as the horses turned around and came back for another pass. Astley's innovation was to set up the performance area as a ring in which the horses would run. Not only would the horses be in view the whole time, the centripetal force as the horses went around the ring helped the riders keep their places during their tricks. He began by using a 62-foot diameter ring, but he soon reduced it to a 42-foot ring, which is still the standard size for circus rings today.

By 1770, the popularity of Astley's performances had far overshadowed his teaching of horsemanship. Knowing a good thing when he saw one, Astley then hired acrobats, tightrope dancers, and jugglers to perform between the horse acts to keep the audience interested in the show.

The circus arrived in America in 1793, presented by British equestrian John Bill Ricketts. George Washington saw this circus and even sold Ricketts a horse for the show.

The wide open spaces in America caused the American circus to naturally gravitate to the railroad as a means of transportation. Railroads generally went between large cities, and large cities meant large crowds. The American circus had to expand from one ring to three to accommodate these crowds. In 1872, P. T. Barnum was the first to put a circus on the rails.

Showmen such as P. T. Barnum dramatically increased the size of the circus. Barnum invested heavily in circus animals, including "Jumbo," the world's largest elephant, which he bought for $30,000.

Many musical instruments were invented specifically for use in the circus, such as the steam calliope (steam-driven whistles), the una-fon (a series of doorbells connected to a keyboard), Shaker chimes (chimes that make unusual sounds when shaken, similar to an ancient Indonesian instrument, the anklung), and the Aluminum Harp (a series of tubes that produce tones when rubbed with rosined gloves).

By the beginning of the twenty-first century, animal rights laws and an explosion of other entertainment opportunities for the general public had caused the circus industry to decline and fragment. Smaller, more polished circuses such as the Cirque du Soleil flourished by performing without animals for niche audiences in the largest cities. The large circuses like Ringling Brothers and Barnum and Bailey Circus faded in cultural importance, though they persist still.