Which ruler began construction of the Lighthouse of Alexandria?

Ptolemy I Soter began construction of the Lighthouse of Alexandria.

Ptolemy I was a Macedonian general who became ruler of Egypt after the death of Alexander the Great. He established the Ptolemaic dynasty and made Alexandria a major political, commercial, and intellectual center. Construction of the lighthouse began during his reign in the early third century BC.

The project was completed under his son, Ptolemy II Philadelphus. This distinction explains why both rulers appear in accounts of the monument: one initiated the work, while the other finished it.

The lighthouse stood on Pharos, an island at Alexandria’s harbor entrance. It served as a navigational landmark and became so famous that the word “pharos” influenced terms for lighthouse in several languages. Earthquakes eventually destroyed the structure.