The final temple to be built on the Acropolis was a marble structure dedicated to Athena Nike. The bastion immediately south-west of the gateway to the Acropolis had accommodated the cult of Athena Nike since the first half of the 6th century BC. At some time, perhaps as late as the mid-5th century BC, a small naiskos (shrine) of poros limestone had been built to enclose an early base, and a new monolithic limestone altar with mouldings had been erected to its east, replacing an earlier altar. The naiskos in turn was replaced by the Ionic amphiprostyle temple, reconstructed on the site today. Its small scale counteracts the bulky proportions of its columns, which have capitals almost identical to those of the Propylaia, though half their size. Work on the temple probably began c. 435–425 BC. While later than the Propylaia, it was clearly already planned before the Propylaia had progressed far. The architect is unknown. Towards the end of the 5th century BC a sculpted parapet was added around the edge of the bastion.