1. The Gemara discusses whether the Aron was hidden or exiled.
2. The Gemara quotes a third opinion in this dispute (#1).
3. D'Vei Rebbi Yishmael supports this opinion (#2) with a story.
4. There were thirteen curtains in the Beis ha'Mikdash.
5. There is dispute about which was the place from which the rest of the world was created.
A BIT MORE
1. Rebbi Eliezer: It was exiled to Bavel. Rebbi Shimon ben Yochai: It was hidden in the Kodesh ha'Kodashim.
2. The Chachamim say that it was hidden underground in the chamber where the wood was kept in the Beis ha'Mikdash. This is supported by a Mishnah in Shekalim that says that there was a Kohen who died while chopping wood in the second Beis ha'Mikdash because he spotted the area where the Aron was hidden.
3. Two Kohanim were chopping wood in the Wood Chamber of the second Beis ha'Mikdash when one of their axes fell to the floor in a section of the chamber. It immediately was consumed by fire, indicating that this was where the Aron was hidden.
4. Seven curtains were by the seven gates, one by the opening of the Ulam, one by the opening of the Heichal, two between the Kodesh ha'Kodashim and the Heichal, and two opposite them between the upper floor of the Kodesh ha'Kodashim and the upper floor of the Heichal.
5. One opinion is that it was created from Yerushalayim. Another opinion is that it was created from the middle of the Earth, and another is that it started from the sides.