Where is "El Kisfos ha'Ulam"?
Rashi: To the two sides of the opening. Vilna Gaon - the wall of the Ulam on the side of Ezras Yisrael was three Amos wide. It was open in the middle; the sides are called Kisfos.
What does the verse teach about "v'Tzal'os ha'Bayis veha'Ubim"?
Rashi: He showed them to me. Tzal'os are boards that hold the rafters in place. "Ha'Ubim" are big beams (Bava Kama 67a).
Vilna Gaon: Tzal'os are the side walls of the Ulam. They and the Ubim (beams) had forms of date trees.
Malbim: Aside from seeing windows in the Heichal itself (16) (and surely they were more than 15 Amos above the ground, for cells surrounded the Heichal until 15 Amos), there were sealed windows 1 "El Kisfos ha'Ulam" (on both sides of the opening in the east), window were also (a) on v'Tzal'os ha'Bayis (the cells around the Bayis in every direction) and (b) on the Avim, i.e. close to the ceiling, where they had thick beams; (c) in addition to the windows in the middle of the Heichal, he saw windows on windows.
Malbim (40:16): The windows were to bring light to the cells. They were sealed with glass.
