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Foundation engineering and planning for the Colosseum was a very big issue, mostly because of the material that it sits on, clay, and the fact the lake was naturally spring fed and on the site. The engineers ended up designing the foundation with the said drains underneath, and a solid 10' x 4' footing of cement, mortar, limestone. This would support the walls, and it would be "flexible" in that if and when the foundation settled, or if the ground moved, the foundation and walls itself would not move much, if at all. We can thank the foundation as one of the reasons the Colosseum has stood so long with minimal wear, other than the disassembling of it in the Middle Ages. .
The landscaping and design of the rest of the site around the Colosseum was just as grand. Around the amphitheater was a patio approximately 50' wide made of the finest paving stones, complete with drains and water fountains. Pathways led off the patio at even intervals, some going to nearby roads, and others leading on a slight downhill where the rest of the lake (now more like a pond) would have been. Benches and tables would have been built around the [pond] for people to enjoy. The Colosseum is divided into 5 sections vertically, with the lowest levels (closest to the arena floor) being for the highest ranked people, and each consecutive level up for people of lower ranks. While such a seemingly simple design, the complexity of the inner divisions of the structure is phenomenal. The architect had to figure out a way to design an arena that could hold upwards of 50,000 people comfortably, and still be able to efficiently and quickly evacuate them from the building (In fact, it has been proven that officials could, if needed, evacuate the 50,000 people that the Colosseum could hold in 5-8 minutes) . In 72 AD this was no easy task, even today it is not an easy task. To combat this issue, the Colosseum is designed with a total of 80 arched entrances, 76 of these entrances are public, while the remaining four are divided up for Senators, the Emperor/Royal Family, Workers, Players/Fighters.
