Where is the Ten Commandments stone held?

Answer 1

Either the story of the Ten Commandments was an allegory and the tablets did not really exist, or they have long ago been lost and destroyed. Either way, there is no Ten Commandments stone.

Answer:
No one knows for sure where the two Stone Tablets are, despite sensational claims to the contrary. Even 1800 years ago, the Talmud-sages discussed this question (Yoma 53b). The Talmud (ibid.) states two opinions in this matter. According to one opinion, the Ark of the Covenant was carried off by the Babylonians when they destroyed the First Temple.
According to the second opinion, around 35 years before the First Destruction, King Josiah (Yoshiah) hid the Ark with the two Stone Tablets in a secret chamber constructed for this purpose, since it was already apparent that the Temple wouldn't last much longer. The Prophets had been foretelling the destruction of the Temple for some time.
Tradition states that when he built the Temple, King Solomon prepared a hidden shaft and room deep underneath the Temple Mount for just such an eventuality (Maimonides, in the Hilchot Beit HaBechirah 4:1).
The second opinion is the accepted one (Maimonides, ibid, 4:1-2). However, it is possible to account for both opinions, since all of the Temple vessels had duplicates which were made in order to be used if the original vessel got lost or defiled (Talmud, Hagigah 26b). We may postulate that the Babylonians carried into captivity an empty duplicate Ark which had been placed in the Holy of Holies after King Josiah concealed the original.