Shipwrecks & Lost Worlds - Tura: the source of ancient Egypt's finest limestone

Located halfway between Cairo and Helwan, the ancient site of Tura served as ancient Egypt's primary source of limestone. The stone originated in the Mokattam Formation, deposited roughly forty-two million years ago during the Eocene epoch, and has yielded fossil fish species. The Egyptians called the area Troyu or Royu. When the ancient Greek geographer Strabo visited, he misinterpreted the native name, assuming it referred to Trojan inhabitants, which led the Hellenistic settlement at the location to be named Troia.

Source: Wikipedia