'Built an Altar' in the Bible

And Moses built an altar, and called the name of it Jehovahnissi:

And Moses wrote all the words of Jehovah, and rose up early in the morning, and built an altar under the mountain, and twelve pillars, according to the twelve tribes of Israel.

And when Aaron saw it, he built an altar before it; and Aaron made proclamation, and said, To morrow is a feast to the LORD.