Big Top is ______.

Today I’ll give you a talk on circus in ancient time. After the talk, we are going to watch a 20-minute video show of Sanduyak Great Circus.
    A circus is a big show in which there are many different acts put on by acrobats, clowns and other performers, dogs, horses, and wild animals of many kinds. The show is given in a huge, high tent called a "Big Top". On the ground there are one or more circle-shaped areas, called rings, in which the main acts are put on. There may be one, two or three rings. The biggest circuses are three-ring circuses, with three different acts, usually going on at the same time.
    Circuss go back more than two thousand years, to Roman time. Roman circuses were held in open arenas, usually U-shaped. Rows of seats rose on the sides on the arenas, as they do in a modern circus tent. On the ground inside the arena was a wide track for chariot races, which was the favorite attraction of the circus. The chariots were pulled by horses. Sometimes there were four horses hitched to each chariot, but in most races there was three horses to each chariot.
    Another great favorite in the Roman circuses was a fight between a man and an animal. Sometimes the man, called a gladiator, fought a bear. Other times he fought a lion, or some other wild animal.
    The circuses in Rome were always held on the eight festival days throughout the year. There were four circus arenas in Rome. The most famous one was the Circus Maximus. It was rebuilt many times after fire destroyed the rows of wooden seats. The emperors or rulers often made changes in the decorations of the arena to suit their fancies. Before the decline of Rome the circuses had become very ornate and colorful. They looked almost as gaudy then as the modern circus does today.