Limestone, like travertine, is a sedimentary type of natural stone that is formed over millions of years as minerals and materials settled and hardened in the earth. As an inherent display of their antiquity, many limestones possess small remnants of fossils within their structure. The organisms and detritus that served to create those fossils have all long since faded into oblivion, but their prints remain in the surface of various limestones as an eternal reminder of its lineage.
Perhaps it is because of the beauty in limestone, or perhaps that many cave formations and natural structures are constituted by limestones, that mankind began at an early point in history using it for various purposes, chief amongst them buildings. An extremely well-known monument of limestone buildings is the Great Pyramid of Giza, one of the most iconic and enduring structures in the world. In fact, it is the only remaining building that was among the Seven Wonders of the Ancient World.