One of Bali's oldest and most important monuments, this river-valley complex consists of 10 huge candi (shrines) cut out of rock faces. Each is believed to be a memorial to a member of 11th-century Balinese royalty. Legends relate that the whole group was carved out of the rock in one hard-working night by the mighty fingernails of Kebo Iwa. You'll need to be fit to explore here, as access to the valley and shrines is via a steep 250-step staircase.
The five monuments on the eastern riverbank are probably dedicated to King Udayana, Queen Mahendradatta and their sons Airlangga, Anak Wungsu and Marakata. While Airlangga ruled eastern Java, Anak Wungsu ruled Bali. The four monuments on the western side are, by this theory, to Anak Wungsu's chief concubines. Another theory is that the whole complex is dedicated to Anak Wungsu, his wives, concubines and, in the case of the remote 10th candi, to a royal minister.
Sarong hire is included in the ticket cost. Try to arrive early in the morning, so as to beat the ubiquitous crowds. However, you won't beat the souvenir sellers whose stands line the access stairs.