Travertine is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan and cream-colored varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave.
Travertine is one of the most frequently used stones in modern architecture. It is a commonly use for façades, wall cladding, and flooring. The Romans mined deposits of aged, dried, and hardened travertine. Among other structures, they built the Colosseum, the largest building in the world constructed mostly of travertine.