Walking up to the Colosseum through the modern streets of Rome with my wife Brigid made me feel alive. I felt proud to work for a company that designs brick arches because there is no greater proof of masonry’s mastery than in Rome. I also felt insignificant in the physical and historical scope of the Colosseum. The stories of thousands of people who had died and cheered on the spot I was standing are what movies are made of.
The exterior of the Colosseum is made from white travertine stone that was quarried from the local hillside and held together with iron clamps. I was surprised to learn that all of the interior was brick and mortar. I we walked through the arcades and hallways, the tour guide gave a short talk on the significance of Roman technological breakthroughs in the field of masonry. The Romans discovered that masonry strength was not compromised by adding arches to span openings. The strength of the masonry structure increases as weight is dispersed above an arch.
The structural brick arches of the seating areas held up as many as 80,000 people as well as the weight of the masonry above it. The arena itself has a brick underground structure that allowed for trap doors with people and animals below like in the movie Gladiator. The brick jack arches of the arena and ground level doors were brilliantly designed and built.
Using four foot long brick, the Romans constructed the jack arch for functionality. The jack arches that supported the arena floor have a 77 degree skew but the jack arches under the massive seating area are built with a 70 degree skew to support more weight above it. What a marvel of engineering.
