Translated as 'Uncertain Fountain', Twyfelfontein was so named by a farmer who doubted the ability of the spring to sustain his cattle for a long time. The spring is still there, and it is quite possibly due to the presence of water in the arid region that the site has been inhabited for at least 6,000 years, first by hunter-gatherers and later by Khoikhoi herders, both of which used the site for sacred rituals, leaving behind about 2,500 rock carvings and some rock paintings. Twyfelfontein is famous for these prehistoric artworks: it boasts the largest concentration of ancient rock art in the country, and has been declared a UNESCO World Heritage Site. The petroglyphs primarily depict game animals such as giraffe, antelope, elephant and lion, and the oldest carvings may date back 10,000 years, although most are believed to be around 3,000 years old. Visitors are no longer allowed to enter the site without a guide, due to previous vandalism. The uniquely-designed visitor information centre features an exhibition, kiosk and souvenir shop. There are a few other stunning sights in the area around Twyfelfontein, including a unique rock formations called the Organ Pipes, the Doros crater, and the Petrified Forest.