Citadel of Qaitbay

A compact limestone fort on a spit of land at the mouth of Alexandria's Eastern Harbour, with water on three sides. It is a short visit — a keep, a mosque inside it, curtain walls and gun platforms — and the reason to come is what stood here before it.

Walk the ramparts for the view back across the corniche, and look closely at the masonry as you go in.

Look for the reused stone

Set into the walls, especially around the base and the entrance, are blocks that do not match: red Aswan granite columns laid on their sides, and oversized beams of a stone nobody quarried locally. They came from the ruins of the Pharos lighthouse, which collapsed on this exact spot — Qaitbay's builders used what was lying there.

The Pharos of Alexandria stood here: one of the seven wonders of the ancient world, built under Ptolemy II around 280 BCE and, at somewhere above a hundred metres, among the tallest structures on earth for most of the following millennium. A fire burned at the top, reflected out to sea by a mirror, and it was visible for tens of kilometres.

It survived far longer than most of the wonders — well over 1,500 years — and was brought down not by war but by earthquakes, in a sequence culminating in a severe one in 1303 and a final collapse by 1323.

Built from the wreckage

In 1477 Sultan Qaitbay put a fortress on the rubble to defend the harbour against the Ottomans. It was a sensible use of a strategic site and a ready supply of cut stone, and it means the lighthouse is quite literally inside the building you are standing in.

The harbour floor

Most of the Pharos went into the sea. Since 1994, underwater surveys in the Eastern Harbour have mapped thousands of architectural blocks, columns, statues and sphinxes across the seabed just off the fort — including colossal figures thought to have flanked the lighthouse. Some pieces have been raised; most remain where they fell.

Divers can visit parts of the site, and there has been a long-running proposal for an underwater museum. Standing on the ramparts, you are looking at one of the great archaeological sites of the Mediterranean, and almost all of it is under the water in front of you.