Ajanta, Ellora, Elephanta & Mahabalipuram c. 2nd century BCE onward
India's grandest sculptures were not built — they were revealed: whole halls, columns and colossi cut downward and inward from a single living cliff. Ajanta's prayer halls pair carving with the murals this site already honours; Ellora's Kailasa temple — a full-scale temple excavated top-down from one rock — is by many reckonings the largest monolithic structure on earth; Elephanta's great three-faced Shiva broods in its island cave; and at Mahabalipuram the Pallavas carved shore temples, rathas and the vast open-air relief often called the Descent of the Ganga. The audacity still stuns engineers: no scaffolding errors are possible when your building is subtraction.