Middos 1:9 - 2:1

הגיע זמן הנעילה – to lock the gates of the Temple courtyard.

הכהן מבפנים ובן לוי יושב לו מבחוץ – that the Levites were secondary to the Kohanim, as it is stated, (Numbers 18:2): “[You shall also associate with yourself your kinsmen the tribe of Levi, your ancestral tribe,] to be attached to you and to minister to you, [while you and your sons under your charge are before the Tent of the Pact].” Therefore, in the House of Avtinas and in the House of the Spark, which were upper stories, the Kohanim who guarded were above and the Levites were below. But the House of the Hearth which was not other than an arch on the land, there was a Kohen on the inside and a Levite on the outside.

במסבה (winding staircase) – in a cavity/underground places, he walks underneath the Temple (see Talmud Yoma 2a for another interpretation) , for the cavity/underground places was underneath the Temple, and all of the Temple is called בירה /the capitol, as it is written (I Chronicles 29:19): “and to build this Temple for which I have made provision.” But because he had had a nocturnal emission,, he would not walk on the path of the Temple courtyard, but rather on the path in the underground , for we hold that the cavities/underground places were not sanctified.

והנרות דולקים – in the underground cavities from here and there.

במסבה ההולכת תחת החיל – he departs, and does not return to the House of the Hearth because he is a someone who has immersed but must wait until sunset until he is ritually pure. But the Halakha is not according to Rabbi Eliezer ben Yaakov, but rather, as it is taught in the beginning of Tractate Tamid. He came and sat with his brethren, the Kohanim in the House of the Hearth until the gates open when he can go on his way, for even though someone who has immersed but must wait until sunset until he is ritually pure, it is forbidden to enter into the Women’s courtyard, which is the camp of the Levites, for this, they were lenient, because he had been defiled inside.

The Temple Mount was five hundred cubits. It was enclosed by a wall

The greater part of it was on the south; next to that on the east. Meaning, the distance from the wall of the Temple Mount to the wall of the [Temple] Courtyard on the southern side was greater than the distance between those [walls] on the eastern side. And the distance between those [walls] on the eastern side was greater than the distance between them on the northern side. And the northern [side] was greater than the south[ern side].