The cultural development is divided into three distinct periods: precolumbian, colonial, and republican. Important archaeological ruins, gold and silver ornaments, stone monuments, ceramics, and weavings remain from several important pre-Columbian cultures. Major ruins include Tiwanaku, El Fuerte de Samaipata, Inkallaqta and Iskanawaya. The country abounds in other sites that are difficult to reach and have seen little archaeological exploration.