The Roman Colosseum has mysterious holes within its massive walls. Actually, during the time of ancient Roman Empire it was robbed for its hidden materials after the population of the city dramatically declined. Thus, many buildings as the Colosseum became disused.
Thousands of holes were made by workers pilfering the iron for use in creation of other structures or for weaponry
During the construction process, workers used iron clamps in between heavy bricks to secure them together to get rid of use of mortar. After the fall of Rome, this metal material of around 200 tons became highly valued. Moreover, many stones and decorative marble from the amphitheater were taken for the building of St Peter’s Basilica and other structures from the 16th century. Despite the fact that there were serious earthquakes that damaged the Colosseum in previous centuries, it was mostly damaged by people, who reused its materials for other buildings construction.