<P> Around the perimeter of the Colosseum, at a distance of 18 m (59 ft) from the perimeter, was a series of tall stone posts, with five remaining on the eastern side . Various explanations have been advanced for their presence; they may have been a religious boundary, or an outer boundary for ticket checks, or an anchor for the velarium or awning . </P> <P> Right next to the Colosseum is also the Arch of Constantine . </P> <P> The Colosseum was used to host gladiatorial shows as well as a variety of other events . The shows, called munera, were always given by private individuals rather than the state . They had a strong religious element but were also demonstrations 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 the Middle East, and included creatures such as rhinoceros, hippopotamuses, elephants, giraffes, aurochs, wisents, Barbary lions, panthers, leopards, bears, Caspian tigers, 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 . During lunch intervals, executions ad bestias would be staged . Those condemned to death would be sent into the arena, naked and unarmed, to face the beasts of death which would literally tear them to pieces . Other performances would also take place by acrobats and magicians, typically during the intervals . </P> <P> During the early days of the Colosseum, ancient writers recorded that the building was used for naumachiae (more properly known as navalia proelia) or simulated sea battles . Accounts of the inaugural games held by Titus in AD 80 describe it being filled with water for a display of specially trained swimming horses and bulls . There is also an account of a re-enactment of a famous sea battle between the Corcyrean (Corfiot) Greeks and the Corinthians . This has been the subject of some debate among historians; although providing the water would not have been a problem, it is unclear how the arena could have been waterproofed, nor would there have been enough space in the arena for the warships to move around . It has been suggested that the reports either have the location wrong, or that the Colosseum originally featured a wide floodable channel down its central axis (which would later have been replaced by the hypogeum). </P>

How much of the roman colosseum is still standing