The arena itself was 83 metres by 48 metres (272 ft by 157 ft / *** by 163 Roman feet).^[6] It comprised a wooden floor covered by sand (the Latin word for sand is harena or arena), covering an elaborate underground structure called the hypogeum (literally meaning "underground"). Little now remains of the original arena floor, but the hypogeum is still clearly visible. It consisted of a two-level subterranean network of tunnels and cages beneath the arena where gladiators and animals were held before contests began. Eighty vertical shafts provided instant access to the arena for caged animals and scenery pieces concealed underneath; larger hinged platforms, called hegmata, provided access for elephants and the like. It was restructured on numerous occasions; at least twelve different phases of construction can be seen.

The hypogeum was connected by underground tunnels to a number of points outside the Colosseum. Animals and performers were brought through the tunnel from nearby stables, with the gladiators' barracks at the Ludus Magnus to the east also being connected by tunnels. Separate tunnels were provided for the Emperor and the Vestal Virgins to permit them to enter and exit the Colosseum without needing to pass through the crowds.

Substantial quantities of machinery also existed in the hypogeum. Elevators and pulleys raised and lowered scenery and props, as well as lifting caged animals to the surface for release. There is evidence for the existence of major hydraulic mechanisms  and according to ancient accounts; it was possible to flood the arena rapidly, presumably via a connection to a nearby aqueduct.

The Colosseum was used to host gladiatorial shows as well as a variety of other events. The shows, called munera, were always given by individuals rather than the state. They had a strong religious element but were also demonstration of power and family prestige, and were immensely popular with the population. Another popular type of show was the animal hunt, or venatio. This utilized a great variety of wild beasts, mainly imported from Africa, and included creatures such as rhinoceros, hippos, elephants, giraffes, lions, panthers, leopards, crocodiles and ostriches. Battles and hunts were often staged amid elaborate sets with movable trees and buildings. Such events were occasionally on a huge scale; Trajan is said to have celebrated his victories in Dacia in 107 with contests involving 11,000 animals and 10,000 gladiators over the course of 123 days. The Colosseum today is now a major tourist attraction in Rome with thousands of tourists each year paying to view the interior arena, There is now a museum dedicated to Eros located in the upper floor of the outer wall of the building. Part of the arena floor has been re-floored

The iconic status of the Colosseum has led it to be featured in numerous films and other items of popular culture:

In the 1953 film Roman Holiday, the Colosseum famously serves as the backdrop for several scenes.

In the 1954 film Demetrius and the Gladiators, the Emperor Caligula anachronistically sentences the Christian Demetrius to fight in the Colosseum.

The conclusion of the 1957 film 20 Million Miles to Earth takes place at the Colosseum.

In the 1972 film Way of the Dragon, Bruce Lee fought Chuck Norris in the Colosseum.

In Ridley Scott's 2000 film Gladiator, the Colosseum was re-created via computer-generated imagery (CGI) to "restore" it to the glory of its heyday in the 2nd century. The depiction of the building itself is generally accurate and it gives a good impression of what the underground hypogeum would have been like.

In the 2008 film Jumper, the Colosseum was used as the location for one of the battles between the jumpers and those trying to kill them.

The Gladiators

The Roman gladiators, whose name comes from the antique Roman sword "gladius", were for the main part war prisoners, slaves or persons sentenced to death. To the spectacles, however, were participating only free men attracted by the rewards and glory, but whoever decided to become gladiator was automatically considered "infamis" for the law. We suppose that the gladiator spectacles found their origin in the far back mortuary ceremonies celebrated with the human sacrifice to calm the rage of the hellish Gods and the anxiety of the dead. The fighters were following a hard training in the schools founded by Nerone and Cesare in which they were exposed to tortures and a established order with the repetitive use of restraints with fire and whip.The discipline was hard, with unbending rules and with severe punishments in such a way to have the gladiators become real fighting machines.At the end of the training period all the fighters were grouped in "companies" of exclusive ownership of the Imperator. The challenges were starting by a parade where the gladiators were making their stage entrance on chariots or by foot followed by a group of drummers; once they had reached the podium of the Imperator, they were greeting him with the words "Ave cesare morituri te salutant" ("Ave o Cesare, those who are about to die are greeting you"), then they were going towards the organizer of the games who examined the weapons which were different on the base of the category of the fighter.
The "retiarii", inspired by the God Triton, were fighting half nude armed of a net, a trident and a knife; the "mirmilloni" however had a helmet, a shield and were armed of a sickle, the gladiators, who were part of the category of the "sanniti" were wearing a helmet equipped of crests, a strong armour and were grasping a javelin. The duellists who were chosen were belonging to diverse categories in such a way to make the spectacle more compelling; from some chronicles of the time, in fact, it even seems that the Imperator Nerone, to honour the king of Armenia, Tiridate, made a dwarf fight against a woman. Sometimes the attacks, after having rendered the arms inoffensive, were only simulated but in the main part of the cases the fights were hard and bloody and were ending by the death of one of the gladiators. If the defeated was wounded he could ask for grace by raising the arm, therefore the public was asking for salvation or death with the authority present on the imperial podium, by showing the inch facing downwards, or waving a white handkerchief. The fighters killed, before they were taken away, were approached by two slaves dressed as Caronte and Ermete Psicopompo: one was checking the death by touching with a hot piece of iron, the other, eventually, was giving them the final stroke making then the sign to the "libitinarii" to take the body away dragging it on the arena with a hook. The winners were rewarded with gold palms, money and the immense popularity won above all among women; if the winning gladiator was a slave, after ten victories, which were written on a metallic collar, he was granted back liberty; he could therefore decide if continuing to fight for money or starting other activities such as for example the instructor

in the schools for gladiators.Another game very appreciated by the public was the "venationes" where the gladiators were fighting against ferocious animals such as elephants, hippopotami, lions, bulls, tigers, panthers, and leopards. The hunts could also consist in a challenge between one or more animals contemporaneously, or they could also be a pretext for executions, when the sentenced persons were introduced in the arena without any defence together with the wild beasts.
The "naumachie" were also much appreciated, that consisted in false naval battles, but as they cost a lot in expenses relative to the armament of the ships, they were rarely organized. From time to time were participating, also if the law was forbidding it, women and members of the upper classes, but obviously they were not mixed with the other gladiators and were not fighting up to death.