As a stone that is often used as a decorative addition to the home either inside as flooring or decoration or as a surface on the exterior of a building, travertine is one of the most popular types of stone used in architecture in the modern era. Just about all of the travertine that exists in the United States is imported. Major architectural works in the country such as the Sears Tower contain significant amounts of travertine and this stone is generally obtained from just a few producers in the United States who import the stone from places like Mexico and Turkey.