First came the 7 ancient wonders, but once their glory faded, the world selected a new group of wonders that stand with unmatched engineering prowess. This is the Roman Coliseum.
Roman engineers laid the groundwork form modern infrastructure, and while there still remains many monuments displaying their intelligence, the Coliseum stands as the pinnacle of both Roman engineering and architecture. Built 80 A.D., the Colosseum became the first permanent amphitheater in Rome. It had seating for 50,000 spectators and beneath its elliptical arena existed a labyrinth of passageways and rooms to coordinate elaborate events.
The Colosseum showcased 2 of Roman engineering’s greatest feats, concrete, and vaulted arches. Although Roman concrete was much weaker than modern concrete, it gave the Romans the ability to construct buildings using forms rather than chiseled stone. Until this time, there had never been a building that had so much open space in the wall structure compared to size and height. This was all allowed through the use of vaulted arches, which in turn have allowed the structure to mostly survive intact until today, other than the damages of a strong earthquake in the 14th century.
The Roman emperor, Vespasian, who commissioned the construction of the Colosseum wanted it done at an unprecedented pace. Roman engineers had to get creative to keep up with the tight deadlines. The construction of the Colosseum was also the first use of standardized parts in construction. Rather, objects like stairs and columns were created offsite and brought onto location when needed. Pairing with this, the seats of the amphitheater and the stairs used were built to the same specification, so their parts could easily be interchanged.
In terms of materials, the arches were constructed using cast concrete, which allowed for a homogeneous material structure to distribute loading stresses. Travertine limestone quarried from Tivoli 20 miles away was used for essentially every other part of the structure. An estimated 3.5 million cubic feet of travertine was used in the construction, and it was joined in a way differing from previous construction. Rather than use mortar, roman engineers opted for iron clamps, which would have essentially acted as expansion joints in the structure to resist temperature changes and seismic loading.
Romans were also well known for their advances in water management engineering. Containing 50,000 people in one space was no easy task, and when duty called, the Romans wanted to keep everything as sanitary as possible. The Colosseum contained a framework of terra cotta piping for a water and sewage management system, something that was rarely seen, even in Roman architecture at the time.
No expense was spared in the construction of the structure which eventually rose to 158 feet tall. The structure itself is not circular, rather it takes an elliptical shape with the dimensions of 615 feet by 510 feet. This elliptical shape was designed to create an internal arena of similar characteristics to allow for chariot racing and other track events.
Other than the advances seen in the Colosseum’s construction, Roman engineers designed crowd control right into the structure. The elliptical design was covered in 80 entrances and exits which allowed for a steady flow of foot traffic. Many events lasted upwards of 100 days, so engineers had to plan for repeated traffic flow of over 50,000 people. Based on estimates, the stadium would have been able to have been completed cleared out in only 10 minutes.
Think about that next time you go to a football game.