Which ancient wonder stood at the entrance to Alexandria's harbor?

The Lighthouse of Alexandria stood at the entrance to Alexandria's harbor.

Also called the Pharos of Alexandria, it was built on the island of Pharos during the reigns of Ptolemy I and Ptolemy II in Hellenistic Egypt. Ancient accounts place its completion in the early third century BCE. The tower guided ships toward the city's harbor and became so famous that “Pharos” influenced words for lighthouse in several languages.

The structure was probably built in several tapering levels, with a square lower section, an octagonal middle section, and a cylindrical upper section. A fire at the top may have been paired with a reflective surface to extend its visibility, although details of the lighting system are uncertain.

Earthquakes damaged the lighthouse over many centuries, and it had largely disappeared by the fifteenth century. Stones from the site were incorporated into the medieval Fort Qaitbay. The lighthouse is one of the traditional Seven Wonders of the Ancient World.