Ancient
Construction of the Colosseum began under the rule of the Emperor Vespasian in around 70–72AD. The site chosen was a flat area on the floor of a low valley between the Caelian, Esquiline and Palatine Hills, through which a canalised stream ran. By the 2nd century BC the area was densely inhabited. It was devastated by the Great Fire of Rome in AD 64, following which Nero seized much of the area to add to his personal domain. He built the grandiose Domus Aurea on the site, in front of which he created an artificial lake surrounded by pavilions, gardens and porticoes. The existing Aqua Claudia aqueduct was extended to supply water to the area and the gigantic bronze Colossus of Nero was set up nearby at the entrance to the Domus Aurea.
The Colosseum had been completed up to the third story by the time of Vespasian's death in 79. Dio Cassius recounts that over 9,000 wild animals were killed during the inaugural games of the amphitheatre. he building was remodelled further under Vespasian's younger son, the newly-designated Emperor Domitian, who constructed the hypogeum, a series of underground tunnels used to house animals and slaves. He also added a gallery to the top of the Colosseum to increase its seating capacity.
In 217, the Colosseum was badly damaged by a major fire (caused by lightning, according to Dio Cassius) which destroyed the wooden upper levels of the amphitheatre's interior. It was not fully repaired until about 240 and underwent further repairs in 250 or 252 and again in 320. The arena continued to be used for contests well into the 6th century, with gladiatorial fights last mentioned around 435. Animal hunts continued until at least 523.
Medieval
The Colosseum underwent several radical changes of use during the medieval period. By the late 6th century a small church had been built into the structure of the amphitheatre, though this apparently did not confer any particular religious significance on the building as a whole. The Colosseum underwent several radical changes of use during the medieval period. By the late 6th century a small church had been built into the structure of the amphitheatre, though this apparently did not confer any particular religious significance on the building as a whole.
A religious order moved into the northern third of the Colosseum in the mid-14th century and continued to inhabit it until as late as the early 19th century. The bronze clamps which held the stonework together were pried or hacked out of the walls, leaving numerous pockmarks which still scar the building today.
Modern
During the 16th and 17th century, Church officials sought a productive role for the vast derelict hulk of the Colosseum. Pope Sixtus V (1585–1590) planned to turn the building into a wool factory to provide employment for Rome's prostitutes, though this proposal fell through with his premature death. In 1671 Cardinal Altieri authorized its use for bullfights; a public outcry caused the idea to be hastily abandoned. The Colosseum is today one of Rome's most popular tourist attractions, receiving millions of visitors annually. The effects of pollution and general deterioration over time prompted a major restoration programme carried out between 1993 and 2000, at a cost of 40 billion Italian lire ($19.3m / €20.6m at 2000 prices).
Since that time, as a gesture against the death penalty, the local authorities of Rome change the color of the Colosseum's night time illumination from white to gold whenever a person condemned to the death penalty anywhere in the world gets their sentence commuted or is released, or if a jurisdiction abolishes the death penalty. Most recently, the Colosseum was illuminated in gold when capital punishment was abolished in the American state of New Jersey in December 2007.
On July 7, 2007, the Colosseum was voted as one of New Open World Corporation's New Seven Wonders of the World.