 The Older or Pre-Parthenon, as it is frequently referred to, was still under construction when the Persians sacked the city in 480 BC and razed the Acropolis.The existence of both the proto-Parthenon and its destruction were known from Herodotus, and the drums of its columns were plainly visible built into the curtain wall north of the Erechtheion.Further physical evidence of this structure was revealed with the excavations of Panagiotis Kavvadias of 1885–90.