* The destruction of Babylon: Babylon was a powerful city-state in Mesopotamia, and its history spans millennia. It was conquered and destroyed multiple times, with the most significant destruction occurring in 539 BCE by the Persian King Cyrus the Great. Other notable destructions include those by the Elamites and the Assyrians.
* The construction of the first library: While the concept of a library predates any specific recorded instance, the most famous early library is the Library of Alexandria, established in the 3rd century BCE in ancient Egypt. The exact founder is debated, with claims for Ptolemy I Soter or his son Ptolemy II Philadelphus.
Therefore, there is no single person or event that both destroyed ancient Babylon and built the first library. These events are separate and occurred in different locations and time periods.