Underneath the layers of vegetation covering the hills in Visoko, there are layers of concrete making up what is known as the Bosnian Valley of the Pyramids.
One of the Bosnian Pyramids, the Pyramid of the Sun, is approximately one third taller than the ancient Egyptian Great Pyramid. The Pyramid of the Sun is constructed of five thick layers of concrete (sandstone slabs, almost one meter thick for each layer), with each layer containing a fifteen centimeter layer of clay in between. Underneath the concrete and clay, the inner pyramid consists of sandstone blocks.
