Side-ring EXTRA · Be-makom kadosh
The phrase “in a holy place” is expounded in Toras Kohanim and Yoma: the immersions of the day (except the first) must occur in a place sanctified with the holiness of the azarah.
English: “In a holy place” — sanctified with the holiness of the courtyard; it was on the roof of Beis HaParvah.
Sanctity of the immersion site
Four of the five immersions of Yom Kippur must take place inside the sanctified precincts. Only the first immersion (before the morning tamid) may be performed outside the azarah.