Although free-standing structural temples were being built by the 5th century, rock-cut cave temples continued to be built in parallel. Later rock-cut cave architecture became more sophisticated, as in the Ellora Caves. The monolithic Kailash Temple is considered to be the peak of this type construction. Although cave temples continued to be built until the 12th century, rock-cut architecture became almost totally structural in nature. That is, rocks were cut into bricks and used to build free-standing structures. Kailash was the last spectacular rock-cut excavated temple. Numerous rock reliefs, relief sculptures carved into rock faces, have been found outside caves or at other sites. New discoveries of relatively small rock-cut sites, mostly Buddhist, continue to be made in the 21st century, especially in the Deccan.