The Gemara states that the kerashim (wall beams) of the Mishkan will remain “standing forever.” This fits nicely with the account in Sotah 9a where we learn that the Mishkan components were hidden away when the First Beis Hamikdash was built. According to one approach, these components were stored in the upper level of the Heychal.
As the sun prepares to set on the day of Yom Kippur, the Kohen Gadol enters the Kodesh Hakodashim one final time to retrieve the empty Ketores ladle and shovel of coals. The room must have been quite dark since the Kohen Gadol carried no lamp with him, and the glowing coals in the shovel had long since expired, and the flames of the nearby Menorah were blocked from view by the curtains of the amah traksin.