The ancient structure that symbolizes ancient Rome's engineering prowess is the Colosseum, also known as the Flavian Amphitheatre. Completed in 80 AD, it is one of the largest and most iconic amphitheaters in the world. The Colosseum could hold tens of thousands of spectators and was used for various public spectacles, including gladiatorial contests, animal hunts, and mock sea battles. Its innovative design and construction techniques, such as the use of arches, vaults, and concrete, reflect the advanced engineering skills of the Romans. Today, it stands as a testament to Rome’s architectural legacy.