The Colosseum was — and still is — colossal. It's the great example of ancient Roman engineering. It was begun in AD 72 during the reign of Emperor Vespasian when the Empire was nearing its peak.

Using Roman-pioneered concrete, brick, and their trademark round arches, Romans constructed much larger buildings than the Greeks.

But, it seems, they still respected the fine points of Greek culture. They decorated their no nonsense mega structure with all three Greek orders of columns — Doric…Ionic…and Corinthian.

Stepping inside, you can almost hear the roar of ancient Rome. Take a moment to imagine the place in action. Romans filled and emptied the Colosseum's 50,000 seats as quickly and efficiently as we do our super stadiums today.

It's built with two theaters facing each other — that's what an amphitheater is — so twice as many people could enjoy the entertainment.

Canvas awnings were hoisted over the stadium to give protection from the sun.

These passageways underneath the arena were covered by a wooden floor. Between acts, animals and gladiators were shuffled around out of sight.

Ancient Romans, whose taste for violence exceeded even modern America’s, came to the Colosseum to unwind. Gladiators, criminals, and wild animals fought to the death, providing the public with a festival of gore. To celebrate the Colosseum's grand opening, Romans were treated to the slaughter of 5000 animals.