The Underground Mosque, Sumur Gumuling, is part of the Taman Sari complex in Yogyakarta in Indonesia. The underground mosque is part of the Taman Sari Water Castle complex. The etymology of the name Taman Sari is Javanese and comes from Taman meaning 'garden' and Sari which means 'beautiful'. During the 18th century the Sultanate of Yogyakarta began work on Taman Sari Water Complex. Comprised of lavish gardens and pools, Taman Sari also featured a mysterious man made sea, connected underneath the ground in a system of tunnels. One of these structures was used as a mosque. This mysterious subterranean mosque has a niche in the wall that was used as a mihrab. The central area is an elevated platform where four staircases meet, and then from the platform one staircase reaches the first floor. The ground level was a small pool used for ritual ablution.