The Pnyx was protected by a defense wall built in the fourth century BC and reconstructed a century later. The new walls, made of almost solid masonry and ashlar blocks, were two-meter thick. The stretch began on a northern end with a tower that stood south of the Melitides Gate of the Themistoclean Wall and ended at the western end of the summit where it joined the Diateichisma. The wall featured seven towers set with 40-meter interval while the connecting walls were strengthened by buttresses.