Candi Sambisari is a 9th-century Hindu temple complex near Kalasan, east of Yogyakarta, notable because it sits several metres below the surrounding ground. The temple was buried by volcanic material and only rediscovered in the 20th century, which is why visitors now look down into a neatly excavated courtyard rather than up at a hilltop shrine.
It is smaller than Prambanan and far less busy, but the sunken setting makes it memorable. The central shrine, guardian figures, and grassy excavation pit give a clear sense of archaeology in progress, even after restoration. Combine it with other Sleman and Kalasan temples if you want a fuller day of lesser-known ancient sites.