The amphitheatre of the Flaviens is called " Colosseum " since the Middle Ages and represents the vastest amphitheatre of the ancient world. It forms an ellipse of 527m of circumference. Some 100 000 m3 of crossbeam were necessary and 300 tons of iron for the metal cramps binding the blocks between them (torn off at the Middle Ages, they leave innumerable holes in the stone).