The answer is: Darius

Ezra 6:15 - The renewed effort of building had started on 21st September 520BC and a sustained effort had continued for almost three and a half years. The temple was completed on 12th March 516BC, almost 70 years after its destruction during the sixth year of the reign of King Darius.

Darius, the king when the second temple was completed, is such a fascinating figure! He ruled from 522 to 486 BC and is often known as Darius the Great. What’s really interesting about him is that while a Persian king, he allowed the Jewish people to return from Babylonian exile and even supported the rebuilding of the temple in Jerusalem! This indicates his permissive and even tactical position towards subordinate peoples – a unique approach for his time.

When you think about the culmination of the temple's reconstruction, it didn’t just bring about the return of a physical center for worship, but it also reignited spiritual hope after years of exile in Babylon. Picture the community coming together after such a long separation from their sacred sites! It's kind of like a family reunion but on a much grander and holy scale.

Moreover, the defining date of March 12, 516 BC gives us a sense of cosmic timing. The temple was built just a few years shy of seventy—a number that often symbolizes a complete period of time in the Bible. It’s almost as if the universe itself aligned for this moment. Plus, you can see echoes of this rebuilding theme throughout the Bible, especially in narratives that highlight human resilience in adversity. The focus on renewal highlights an ongoing theme: that regardless of how trying circumstances may be, a chance for revitalization always lies ahead. Isn’t that a hopeful concept?