Gunung Leuser National Park is a national park covering 7,927 km² in northern Sumatra, Indonesia, straddling the border of North Sumatra and Aceh provinces. The national park, named after 3,381 m height of Mount Leuser, protects a wide range of ecosystems. An orang-utan sanctuary of Bukit Lawang (this is the place which I did visit) is located inside the park. Together with Bukit Barisan Selatan and Kerinci Seblat national parks it forms a World Heritage Site, Tropical Rainforest Heritage of Sumatra.