Tiwanaku is a ruined ancient city near Lake Titicaca in western Bolivia. Dominating the ruins, once the seat of the pre-Columbian Tiwanaku culture, are the Akapana pyramid and a semi-subterranean temple with carved images of human heads. Nearby Kalasasaya is an open temple with stone monoliths and the huge Gate of the Sun arch. The Museo del Sitio de Tiwanaku displays artifacts excavated from the site.