Ezra 6:13

Then Tatnai, governor on this side the river, Shethar-boznai, and their companions, according to that which Darius the king had sent, so they did speedily.

Then Tatnai ... did speedily. A concurrence of favourable events is mentioned as accelerating the restoration of the temple, and infusing a new spirit and energy into the workmen, who now laboured with unabating assiduity until it was brought to a completion. Its foundation was laid in April, 536 BC (Ezra 3:8), and it was completed on 21st February, 515 BC, being 21 years after it was begun (Lightfoot). The building having been stopped, was resumed on the 24th day of the ninth month, in the second year of Darius, and finished on the third day of the twelfth month, in the sixth year of his reign. Four years and a quarter were occupied from the recommencement to the completion of the work.