World and the most famous lighthouse in antiquity. It was a technological triumph and is the archetype of all lighthouses since. Built by Sostratus of Cnidus, perhaps for Ptolemy I Soter, it was finished during the reign of Soter’s son Ptolemy II of Egypt in about 280 bce. The lighthouse stood on the island of Pharos in the harbour of Alexandria and is said to have been more than 350 feet (110 metres) high; the only taller man-made structures at the time would have been the pyramids of Giza. Much of what is known about the structure of the lighthouse comes from a 1909 work by Hermann Thiersch, Pharos, antike, Islam und Occident. According to the ancient sources consulted by Thiersch, the lighthouse was built in three stages, all sloping slightly inward; the lowest was square, the next octagonal, and the top cylindrical. A broad spiral ramp led to the top, where a fire burned at night.