7.7700°S, 110.4889°E.
Ratu Boko is a hilltop palace and ceremonial complex in central Java, Indonesia, built between approximately 760 and 810 CE under the Sailendra dynasty and later modified by the Sanjaya kings. The site sits on a plateau 196 metres above sea level overlooking the Prambanan plain and the Merapi volcano to the north. Unlike the surrounding temple complexes, Ratu Boko was designed as a royal residence and audience complex, with a great gateway, a paved central plaza, an elevated audience pavilion, water tanks, ritual bathing pools, and a series of meditation caves cut into the volcanic rock. Construction is in andesite stone and contrasting white limestone. The Abhayagirivihara inscription of 792 CE indicates the site was originally a Buddhist monastic foundation for monks from Sri Lanka before its later conversion to a Hindu palace. Dutch archaeologist Arend Hulshoff excavated the site in 1925-29.
The dramatic gate structure still stands, opening across the plateau toward the distant Prambanan towers below.