Mishnà su Ezechiele 43:16

The altar was thirty-two cubits by thirty-two. It rose a cubit and went in a cubit, and this formed the foundation, leaving thirty cubits by thirty. It then rose five cubits and went in one cubit, and this formed the surround, leaving twenty-eight cubits by twenty-eight. The horns extended a cubit in each direction, thus leaving twenty-six by twenty-six. A cubit on every side was allowed for the priests to go round, thus leaving twenty-four by twenty-four as the place for the wood pile [for the altar fire]. Rabbi Yose said: Originally, the complete area [occupied by the altar] was only twenty-eight cubits by twenty-eight, and it rose with the dimensions mentioned until the space left for the altar pile was only twenty by twenty. When, however, the children of the exile returned, they added four cubits on the north, and four on the west like a gamma, since it is said: “Now the hearth shall be twelve cubits long by twelve broad, square” (Ezekiel 43:16). Is it possible that it was only twelve cubits by twelve? When it says, “With four equal sides” (ibid), this shows that he was measuring from the middle, twelve cubits in every direction. A line of red paint ran round it in the middle to divide between the upper and the lower blood. The foundation ran the whole length of the north and of the west sides, and it took up one cubit on the south and one on the east.