"Lost technologies" refer to advanced methods or inventions that were once known but have been forgotten or are no longer in use. These technologies often include ancient engineering techniques, such as those used in the construction of the Great Pyramids or the Roman aqueducts, which showcased remarkable skills that modern society sometimes struggles to replicate. Many lost technologies are linked to specific cultures or historical periods, like the Antikythera mechanism, an ancient Greek analog computer. The reasons for their loss can vary, including societal collapse, lack of documentation, or the evolution of new technologies that rendered them obsolete.