Shekalim 6:1-2

Shekalim 6:1

In the Temple there were 13 shofar-shaped chests, 13 tables and 13 places where people would prostrate. The house of Rabban Gamliel and the house of Rabbi Chanina, the deputy High Priest, prostrated in 14 places. The extra place was across from the chamber where firewood was kept since they had a tradition that that’s where the Ark had been hidden.

Shekalim 6:2

It once happened that a certain kohein was involved with his work and he noticed that the section of floor where he was working differed from the rest. He told his friend but he died before he could reveal the location. From this they inferred that it was the area where the Ark had been concealed.