A megalith is a large prehistoric stone that has been used to construct a structure or monument, either alone or together with other stones. There are over 35,000 in Europe alone, located widely from Sweden to the Mediterranean sea. The word was first used in 1849 by the British antiquarian Algernon Herbert in reference to Stonehenge and derives from the Ancient Greek. Most extant megaliths were erected between the Neolithic period (although earlier Mesolithic examples are known) through the Chalcolithic period and into the Bronze Age.