In the northeastern corner of the Ezras Nashim was the Chamber of the Eitzim. Here the Kohanim would inspect firewood to determine if it was infested with worms, since any piece of wood containing worms was not fit to be burned upon the Mizbeyach. This wormy wood was not discarded but rather was used for other purposes in the Beis Hamikdash, such as fueling the various warming fires or the stoves used for cooking sacrificial meat.
Trees destined to be used as wood for the Mizbeyach would be harvested from 1 Nisan through 15 Av. After 15 Av the power of the sun began to wane and could not sufficiently dry out the trees. The increased moisture content in the wood caused it to smoke when burned and also promoted infestation by worms, neither of which were desirable. The final day of the tree harvest, 15 Av, was celebrated as a holiday known as “Breaking of the Hatchet” to mark the conclusion of this great undertaking.
In the Second Beis Hamikdash the Aron was not present, having been concealed in a labyrinth of underground tunnels before the First Beis Hamikdash was destroyed. Our Gemara quotes an incident regarding a loose floor tile in the Chamber of the Eitzim that seems to place this labyrinth underneath this room. Although it would have been an easy task to search the chamber and locate the tile, the Kohanim understood that Hashem did not yet want the secret tunnel to be revealed and they decided not to investigate the matter further.