Upon his bases - They restored the old altar of burnt-offerings, which stood directly in front of the temple-porch, upon the old foundation. This became apparent on the clearing away of the ruins, and on a careful examination of the site.
Related Commentaries of Ezra 3:3
Ezra 3:3
3 And they set the altar upon his bases; for fear was upon them because of the people of those countries: and they offered burnt offerings thereon unto the LORD, even burnt offerings morning and evening.