A tall, four-sided pillar of stone, usually tapering, that terminates in a pyramid. Obelisks were placed at the entrances of ancient Egyptian temples. Several Egyptian obelisks were transported to Rome as trophies by the Roman emperors. Obelisks continued to be used as monuments in the Western world in the 18th,19th and 20th centuries. Web resources here and here.

Obelisk of Thutmose I, Karnak, Egypt. Rose granite. New Kingdom. 1493/1492–1479 BCE.