How Did Holy Temples of Stone Burn?
Both our Holy Temples were set aflame, and were told that they burned for quite a while. The First Temple was set ablaze on the 9th of Av close to nightfall and continued burning through the 10th of Av, to the point that some sages felt that the fast commemorating the destruction should have been established on 10 Av, when most of the Temple was burned. Actually, it was generally prohibited to have exposed wood in the construction of the Temple. That being the case, only a minimal amount of wood was used as support beams and the (very high) ceiling. So, although there were wooden support beams in parts of the First Temple, the wood was specifically used higher up in the structure and covered with plaster, which would have prevented it from burning. Additionally, the stone walls themselves were six cubits (at least 9 feet) thick in most places! Now we are far from the first ones to think of how the Temple could be burned. In fact, Cyrus, when giving the initial go ahead to build the Second Temple, specified that he wanted it built with alternating rows of stone and wood (lower down) precisely in order that it be easily burnt should the desire arise. Nevertheless the fact remains that the Temples were constructed primarily of stone. This is especially true regarding the structure commissioned by Herod, which is what the Romans burned down. Now, it is true that some of the Second Temple structure remained standing even after the initial destruction and was plowed over only many years later by the Romans. However, that still doesnt quite answer our question of what actually burned for so long on Tisha BAv.