The Callanish (or Calanais) Stones of Lewis are some of the most famous standing stones in Scotland. They date back to 2000-1500 BC. There are about 50 stones altogether, with 13 stones of 8-13 feet in height surrounding the central monolith which is 16 feet high and weighs approximately 5.5 tons. The stones gradually fell out of use and were being slowly enveloped by encroaching peat by about 800 AD when a nearby settlement was built. By the time the stones were excavated in 1857, the peat was nearly six feet deep.