There are 34 caves at Ellora, a UNESCO World Heritage Site, hewn out of a 2 km escarpment. The architecture and engineering involved is spectacular in terms of its scale, geometrical accuracy and aesthetics. There are Hindu, Buddhist and Jain temples which have been created either by tunneling horizontally into the rock face or by digging down from the cliff top.
The image, above, with the vaulted ceiling, is the Buddest temple Vishwackarma, so finely carved that it gives the appearance of being made from wood. This cave (#10) also has the most amazing acoustics allowing chanting to seemingly be amplified as it reverberates around.