Above the ground, the northeast corner of the (expanded) Har Habayis can be clearly seen, and to the north of it is the more modern eastern city wall of Yerushalayim. However, underground the Har Habayis wall does not end at this point, but runs further, for another 38.4 meters (126 feet).
Warren writes the following about this (Survey of Western Palestine, Jerusalem, pp 129-130): Gallery along east wall of Sanctuary, Commenced 5th June,1869. From a point (P) 18 feet south of the north-east angle, a gallery was driven along the wall (level 2,363 feet 3 inches [720.31 m]) to north, past where the straight joint between the Castle of Antonia and city wall should occur; but no straight joint was found to exist. The wall runs on without a break of any kind, and there is no projection... To a distance of 65 feet (19.81 m) the stones were all like those at the Wailing Place, but beyond this to 75 feet (22.86 m) they had rough projecting faces (projections about 6 to 10 inches [15-25 cm]) with well-cut marginal drafts.
Some people have tried answering the question by saying that the present northeast corner of Har Habayis is from more recent times, and originally, the northern wall was further to the north, where the eastern wall ends. Since almost the whole present northern wall of the Har Habayis is from more recent times, this theory sounds viable. However, in the eastern corner of the wall, some Herodian stones can be seen, although they are heavily damaged and patched up with smaller, more recent stones. These are not in secondary use, as they are laid in the normal Herodian corner fashion of header and stretcher (see this earlier post).
There must be a different solution to the problem. Directly to the north of the Har Habayis was a large pool of water, the bereichas Yisra'el. This extra part of the eastern wall would have been a dam wall for the front of this pool, and this part of the wall is in fact thicker than the rest of the wall, it is a full 14 m (46 feet) thick! (The rest of the wall, by contrast, is 2.88 meters (9 ft. 6 in.) thick.) This supports the idea that this part of the wall had a separate function than the rest of the wall.
A northern counterpart to Shlomo's stables?
In the southeastern corner of Har Habayis, there are underground vaulted area, known as Shlomo's stables (see my earlier post about them). These were made to support the platform on top, as the original ground sloped downwards in that area. Now, the area under the northeast corner of the Har Habayis also slopes down, and in fact goes slightly lower that the southeast corner. The question that now rises is, were there also underground vaulted area over here?
Rabbeinu Ovadia MiBartenura, in his letters describing his travels to Eretz Yisroel (Darchey Tzion), writes the following about the Har Habayis: "At the north-east corner is a tower of very large stones. I entered it and found a vast edifice supported by massive and lofty pillars; there are so many pillars that it wearied me to go to the end of the building. Everything is filled with earth which has been thrown there from the ruins of the Temple. The Temple-building stands on these columns, and in each of them is a hole through which a cord may be drawn. It is said that the bulls and rams for sacrifice were bound there." However, his description matches perfectly descriptions of Shlomo's stables from that era, and there could be a mistake, and he meant the southeast corner, not the northeast.
Another description of underground vaults in this area is given by Peter Richardson, a tourist who visited the Har Habayis. In a letter to Walter Besant, the secretary of the PEF, he writes the following: "In the year 1867 I was in the Temple area as one of a party of four. After issuing from the Mosque [Dome of the Rock] I asked our guide privately to show me some underground buildings which I know either from testimony or conjecture existed between the Golden Gate and St Stephens [Lion’s Gate]. He denied repeatedly the existence of such buildings, but on my resolutely affirming it he said: ‘Come away then by yourself.’ He took me in a direction, I think, about N.E. from middle of platform of mosque, led me close to eastern wall, showed me a rough hole of 3 of 4 feet in diameter and bade me jump down. On executing this feat, adjusting my eyes to the situation I found myself among a forest of arches, forty or fifty feet high [about 12-15 m]. Of the pillars supporting them I remember nothing now, whether in regard to bulk or character. There was a small opening through which, if I mistake not, the daylight came; and as it seemed to me to be on the northern side of the subterranean structure, it must have communicated with the so-called Pool of Bethesda [Birket Israel]. If that is correct, the Pool, I should think, must be part of a natural depression abutting on the Kedron valley, and the underground buildings artificial support of surface of Haram area. It never occurred to me to doubt that the buildings exist at the spot indicated. The rough entrance, close by Eastern wall, seemed about halfway between Golden gate and northern extremity of Haram". (PEF Archives/WS/71)
Adding this to the testimony of Rabbeinu Ovadia MiBartenura, it seems that there is enough evidence for underground vaults in this area, forming a northern counterpart to Shlomo's stables.
Here are some computer renderings of how it might look, based on the above-mentioned descriptions.
Conder, Claude Reignier, and Warren, Charles. The Survey of Western Palestine: Jerusalem. London, 1884.
Gibson, Shimon. “Archival Notes on Robinson's Arch and the Temple Mount/Haram Al-Sharif in Jerusalem.” Palestine Exploration Quarterly 153.3 (2020): 222–243. Web.
Gibson, Shimon and David Jacobson (1996), Below the Temple Mount in Jerusalem: A Sourcebook on the Cisterns, Subterranean Chambers and Conduits of the Haram Al-Sharif.
Ritmeyer, Leen. The Quest: Revealing the Temple Mount in Jerusalem. Israel: Carta, 2006
I have added the sefer Mishkenei Elyon from the Ramchal on the third Beis Hamikdash, as well as another fife pictures of the third Beis Hamikdash.
My name is Mendel Lewis.
Hashem said to Yechezkel, "Its reading in the Torah is as great as its building. Go and say it to them, and they will occupy themselves to read the form of it in the Torah. And in reward for its reading, that they occupy themselves to read about it, I count it for them as if they were occupied with the building of it. (Tanchuma tzav 14)