The Temple and Temple Mount represent the pinnacle of Herod's architectural achievements. Around 20 BCE the king commenced work on this monumental undertaking, which took approximately nine years. During this time, he dismantled and rebuilt the Second Temple, first built in 519 BCE by Jews who had returned to Jerusalem from exile in Babylonia. Ten-thousand laborers were employed in the construction, along with a 1000 priests who worked in the area forbidden to non-priests. The project involved the artificial extension of the Temple platform, supported by enormous walls, to more than double the area of the original hilltop. On the platform a spacious courtyard was constructed. It had porticoes on three sides and a monumental basilica on the fourth, southern, side. In the center stood the Temple.
Herod was responsible for the construction of several pagan temples inside his kingdom and beyond it, but this project overshadowed them all, for the Temple in Jerusalem was the largest sacred enclosure in the entire Roman world. It was the religious and social center of the Jewish people, and its destruction in 70 CE would have a momentous impact on the development of Judaism both in the Land of Israel and in the Diaspora.