First thing’s first. The real name of this wonder of the world is the Flavian Amphitheater. Tourists and most modern people call this place the Roman Colosseum.
This beautiful work of Roman Architecture was built around 70 to 80 AD and is still the biggest amphitheater ever built. It is made from a mixture of concrete, travertine, and tuff. It sits just across the way from the bottom of the Roman Forum, caddy corner to the Arch of Peace, and down the street from the Palatine Hills entrance.
Its construction began during the reign of Vespasian and completed by his successor Titus during the Flavian dynasty. Further restorations were made during the reign of Domatian, another member of the Flavian dynasty, insuring the name Flavian Amphitheater.
This marvel of architecture is estimated to seat 50,000 to 80,000 people. It was used for gladiatorial games and public spectacles. During the reign of the Romans, this was used almost constantly.
During the Medieval era, the Colosseum fell into disarray. It, along with most of Rome was abandoned and looted. Between stone robbers and natural disasters, the age of the Colosseum shows. It was once one complete oval, but the half-destroyed structure that remains today has become something of an icon representing the eternal city. 
The Colosseum is open until 7 pm daily. The cost for one ticket is set at about $12, but this gets you into the Colosseum, Palatine Hills, and the Roman Forum. For more information on the Colosseum or to plan your visit, click this link!
Allora Studios 