What exactly is the Ark of the Covenant?

The Ark of the Covenant (Hebrew: אָרוֹן הָבְּרִית‎ Ārōn Hāb’rīt [modern pron. Aron Habrit]; Arabic: تابوت العهد‎ Tābūt Al-ʿahd) is a vessel described in the Bible as containing the Tablets of Stone on which the Ten Commandments were inscribed, along with Aaron's rod and manna. According to the Pentateuch, the Ark was built at the command of God, in accord with Moses' prophetic vision on Mount Sinai (Exodus 25:10-16). God was said to have communicated with Moses "from between the two cherubim" on the Ark's cover (Exodus 25:22). The Ark and its sanctuary were considered "the beauty of Israel" (Lamentations 2:1). Rashi and some Midrashim suggest that there were two arks - a temporary one made by Moses himself, and a later one constructed by Bezalel.