TheCyclopean Wall of Rajgir is a 40-kilometre-long (25 mi) wall of stone which encircled the ancient city ofRajgriha (present-dayRajgir), in theIndian state ofBihar, to protect it from external enemies and invaders. It is among the oldest examples ofcyclopean masonry in the world.

It was erected by the earlyMagadha rulers of Haryanka dynasty King Bimbisara and completed by his son and successor King Ajatasattu using massive undressed stones.

Only some portions of it remain. Most of the original structure has disappeared with time. The wall is currently designated as a national monument, and the Bihar Archaeological Department has recommended to theArchaeological Survey of India that it should be included in the list ofUNESCO World Heritage Sites, which was achieved in 1987.^[1][2]

The wall is a type of stonework built with massive limestone boulders, roughly filled together with minimal clearance between adjacent stones and no use of mortar. The boulders typically seem unworked, but some may have been shaped with a hammer.^{[original research?]}