Ark of the Covenant
The second set of the two tablets of stone with God's Covenant engraved on them, commonly known as the Ten Commandments, was placed in a sacred ark that came to be known as the Ark of the Covenant.
The Ark of the Covenant, also known as the Ark of God and the Ark of the Testimony, was made of acacia wood, and was 27 inches in width and height, and 43 inches in length. It was covered all over with the purest gold. Its upper surface or lid, the mercy-seat, was surrounded with a rim of gold; and on each of the two sides were two gold rings, in which were placed two gold-covered poles by which the ark could be carried. Over the ark, on either side and facing each other, sat two cherubim.
The Ark itself was placed in the Holy of Holies, the innermost room of the Tabernacle, and was placed there in such a manner that one end of the poles by which it was carried touched the veil that separated the two apartments of the Tabernacle. During the journeys of the Israelites the ark was carried by the priests in advance of the host. When carried it was always wrapped in the veil, the badgers' skins, and blue cloth, and carefully concealed even from the eyes of the Levites who carried it. Miracles occurred on several occasions.
Now the Jordan is at flood stage all during harvest. Yet as soon as the priests who carried the ark reached the Jordan and their feet touched the water's edge, the water from upstream stopped flowing. It piled up in a heap a great distance away, at a town called Adam in the vicinity of Zarethan, while the water flowing down to the Sea of the Arabah was completely cut off. So the people crossed over opposite Jericho.
A more famous miracle took place at Jericho, where God gave the following instructions to Joshua who stood outside a beseiged city unable to breach its walls. When Joshua obeyed God without question, it happened just as God said.
Then the LORD said to Joshua, "See, I have delivered Jericho into your hands, along with its king and its fighting men. March around the city once with all the armed men. Do this for six days. Have seven priests carry trumpets of rams' horns in front of the ark. On the seventh day, march around the city seven times, with the priests blowing the trumpets. When you hear them sound a long blast on the trumpets, have all the people give a loud shout; then the wall of the city will collapse and the people will go up, every man straight in." (Joshua 6:2-5)
The location of the Ark changed several times, until David finally took it in a grand procession to Jerusalem where a place was kept for it. Years later, during the reign of King Nebuchadnezzar, the Babylonians destroyed Jerusalem and plundered the temple which stored the ark, but there is no record to whether the Ark had been there in the temple at the time, and if it was, what happened to it.
The fate and location of the Ark of the Covenant remains open to much speculation.