Standing stones, also known as menhirs (6 letters), monoliths (8 letters) and steles (5 letters), are large, upright stones that have been used in various cultures throughout history. Menhirs are single standing stones, while monoliths are large, single blocks of stone, and steles are upright stones with inscriptions or carvings. Standing stones have been used for a variety of purposes, including religious ceremonies, marking boundaries, and memorials.