1)
What is "Sha'ar ha'Yeshanah"?
1.
Rashi: This is the name of the gate.
2.
Ibn Ezra: Ha'Yeshanah is an adjective. The noun that it describes is omitted 1 .
3.
Malbim: It was in the northeast. I say that it is Sha'ar ha'Pinah, where Uziyah built towers (Divrei ha'Yamim II, Perek 26).
1
It cannot describe Sha'ar, for Sha'ar is masculine. Also, presumably all the gates were built at the same time! (PF)
