It was built by Sostratus of Cnidus a Greek architect and engineer. The project was started by Ptolemy I Soter and was completed by his son Ptolemy II Philadelphus. The purpose of the imposing work was to increase the safety of incoming and outgoing maritime traffic, made dangerous by the numerous sandbanks in the stretch of sea overlooking the port of Alexandria and the absence of orographic reliefs. It allowed to signal the position of the port to the ships, by day through the special bronze mirror polished that reflected the sunlight to the open sea, while fires were lit at night. It is estimated that the tower was 134 meters high, one of the tallest buildings existing for the time, and the lighthouse, according to the testimony of Josephus, could be seen 48 km away, that is up to the limit allowed by its height and from the curvature of the earth's surface. This is why it is considered the first skyscraper in history.