The Colosseum (Colosseo) was built from Roman Travertine, which is a form of limestone deposited by mineral springs, mostly from hot springs. The material is from Tivoli and it exists in white, tan, cream-colored varieties. Moreover, it is formed during the process of precipitation of calcium carbonate and is frequently used in Italy as a building material. After the Great Jewish Revolt in 70 AD, around 100.000 Jewish prisoners were working on the massive construction. The slaves undertook manual labor. For instance, they transported stone 20 miles from Tivoli to Rome. Along with them, teams of professional Roman engineers, painters, builders and decorators worked on the construction.
The Flavian Amphitheater constructed with wood, limestone, cement, mortar, and tuff materials
Also, famous Marcellus’ theater was built from the travertine. You can find out its modern providers here and here. Also, around the exterior of the Colosseum run three orders of arches: Doric, Ionian and Corinthian, and a fourth floor with Corinthian pilasters. There are 80 arches that create the epiliptical ring, where four of them correspond to entrance of honor reserved for the Emperor remains.