1)
What is "Sha'ar Beis Hashem ha'Elyon"?
1.
Radak: It was a gate between Beis Hashem and Beis ha'Melech.
2)
Did Yosam build this gate? Shlomo built it - "v'Olaso Asher Ya'aleh Beis Hashem" (Melachim I, 10:5)! And it says about Yo'ash "va'Yavo'u b'Soch Sha'ar ha'Elyon Beis ha'Melech" (Divrei ha'Yamim II, 23:20)!
1.
Radak #1: Yosam added to it. Malbim - he built great buildings there.
2.
Radak #2: It had fallen, and Yosam rebuilt it.
