Summit crosses are normally about two to four metres high and are usually made of wood or metal. In April 2010 the world's first glass summit cross was erected on the Schartwand (2,339 m) in Salzburg's Tennengebirge mountains. Summit crosses are mainly found in Catholic regions of the Alps, especially in Austria, Switzerland and Bavaria, mountainous regions of Poland, but also in America. They usually stand on mountains whose summits are above the tree line, but they are also found in the German Central Uplands, for example in the Black Forest on the Herzogenhorn.