The first Mishna of the sixth perek appears on our daf, and it teaches about 13 collection boxes – referred to as shofarot because of their shape – that were in the Temple, a number of which were for the deposit of shekalim. The Mishna continues with a description of other times there were 13 things in the Temple, including shulhanot (tables) and hishtahavayot (times that the people bowed down). The Mishna records another tradition kept by Rabban Gamliel’s family, who bowed down fourteen times. They bowed down an extra time near the storage house for wood because of the tradition that the aron – the Ark of the Covenant – was hidden there.
During the first Temple period, there was a rock in the kodesh kodashim, the Holy of Holies in the Temple, called the even ha-shetiya (foundation stone), upon which rested the aron, together with a container of manna (see Shemot 16:33-34) and Aharon ha-Kohen’s staff (see Bamidbar 17:16-24). During the Second Temple the Mikdash operated without an ark. When the kohen gadol (high priest) entered the Holy of Holies on Yom Kippur, the service was performed in the place of the ark, even though there was none there. The ark was hidden by King Yoshiyahu towards the end of the first Temple period. During his reign, a copy of Sefer Devarim was discovered that was interpreted by Hulda ha-nevi’ah as warning of the destruction of the kingdom (see II Melakhim 22-23). According to the Radak, the discovered scroll was open to the passage (Devarim 28:36) that foretold of the exile, and the king, fearing that if the ark was taken into exile it would never return, chose to hide it on the grounds of the Mikdash (see II Divrei ha-Yamim 35:3).
The mishna relates that there was an incident involving a certain priest who was going about his duties and saw a certain flagstone that was different from the others. He noticed that one of the stones was slightly raised above the others, indicating that it had been removed and returned to its place. The priest understood that this was the opening to an underground tunnel where the Ark was concealed. He came and said to his fellow that he had noticed this deviation in the floor. He did not manage to conclude relating the incident before his soul left him, i.e., he died. Following this event, they knew with certainty that the Ark was sequestered there and that God had prevented that priest from revealing its location.
It should be noted that there is an opinion that the aron was also taken into exile to Babylon, based on II Divrei ha-Yamim 36:10, which describes that the keli hemdat bet ha-Shem (goodly vessel of the house of Hashem) was taken there.