The southeast corner of the (expanded) Har Habayis is built on the lowest point of the bedrock, so in order to help stabilize it, the lower rows of stone are set back from the ones under them more than in the other walls, they are set back between 7.6-10.1 cm (3-4 in), and in one case 15.2 cm (6 in). Higher up (around seven rows under the master course), however, they are set back very little, only a quarter or a third of an inch (around 7 mm). On some of the lowest stones of this corner there are letters and symbols on the stones, either painted with red paint or engraved. The margins of some of these lower stones are very irregular, with some having huge margins on one side, and very small or no margins on the other, it seems that they used unperfect stones for here, since they were below street level, and would never be seen anyway.
When the stones for the Har Habayis were quarried, the masons left small square projections of about 12 cm (4 in), on either side of the stone. These projections had ropes placed around them, and were used to lift and transport the stones. When the stones were put into the Har Habayis walls, these projections were usually cut off, however sometimes they were left, and you can still see stones in the southern edge of the eastern wall which have these projections.
I have added a new video of the Lishkos on the northern side of the first 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)