Yoma 16 - Where exactly was the Altar placed?

When the deputy Kohen would burn the Red Heifer, he had to do it on the Olive Mount, right across the entrance to the Temple building. This is required by the Torah, and we understand from here that he had to actually see the entrance. This was only possible if the eastern wall of the Temple was somewhat lower than the other walls. The Talmud is interested in whose opinion this is. It answers that it could only be Rabbi Elazar ben Yakov since only according to him, that wall’s foundation was high enough for the problem of visibility to arise.

But perhaps this is the opinion of Rabbi Yehudah, since, according to him, the gates' geometry would allow this direct view? - No, it could not be him, because according to Rabbi Yehudah, the Altar was exactly in the middle of the Courtyard and would obstruct the view. Thus, by combining the limitations imposed by the rules of burning the Red Heifer and the Altar position, the Talmud finds who was the author of the rulings we are learning here in Yoma and in the Tractate Midot, which concerns the exact sizes of everything in the Temple.

Art: Jerusalem From The Mount Of Olives by Frederic Edwin Church