'Built an Altar' in the Bible

And Moses built an altar and named it The Lord Is My Banner;

Moses wrote down all the words of the Lord. Then he got up early in the morning, and built an altar [for worship] at the foot of the mountain with twelve pillars (memorial stones) representing the twelve tribes of Israel.

Now when Aaron saw the molten calf, he built an altar before it; and Aaron made a proclamation, and said, “Tomorrow shall be a feast to the Lord!”