'Built an Altar' in the Bible

And Moses built an altar, and called the name of it, The LORD is my banner:

And Moses wrote all the words of the LORD, and rose up early in the morning, and built an altar at the foot of 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, Tomorrow is a feast to the LORD.