Ezekiel 43:16

And the altar is twelve long by twelve broad, square in its four squares.

Exodus 27:1

And thou hast made the altar of shittim wood, five cubits the length, and five cubits the breadth -- the altar is square -- and three cubits its height.

Exodus 38:1-2

And he maketh the altar of burnt-offering of shittim wood, five cubits its length, and five cubits its breadth (square), and three cubits its height;

2 Chronicles 4:1

And he maketh an altar of brass, twenty cubits its length, and twenty cubits its breadth, and ten cubits its height.

Ezra 3:3

And they establish the altar on its bases, because of the fear upon them of the peoples of the lands, and he causeth burnt-offerings to ascend upon it to Jehovah, burnt-offerings for the morning and for the evening.

Treasury of Scripture Knowledge

Summary

And the altar shall be twelve cubits long, twelve broad, square in the four squares thereof.

Square

Bible References

Twelve cubits

Exodus 27:1
And thou hast made the altar of shittim wood, five cubits the length, and five cubits the breadth -- the altar is square -- and three cubits its height.
2 Chronicles 4:1
And he maketh an altar of brass, twenty cubits its length, and twenty cubits its breadth, and ten cubits its height.
Ezra 3:3
And they establish the altar on its bases, because of the fear upon them of the peoples of the lands, and he causeth burnt-offerings to ascend upon it to Jehovah, burnt-offerings for the morning and for the evening.

Square

Exodus 38:1
And he maketh the altar of burnt-offering of shittim wood, five cubits its length, and five cubits its breadth (square), and three cubits its height;