The Ark of the covenant was constructed to place the two tablets that contains the ten commandments. Many have been debated through the centuries about its real content. Some opinions were raised and according to them, there were two Arks created for two tablets and placed separately. It was made up of acacia wood and covered with gold. There were four gold rings attached on the bottom and two poles also made of gold. It's covering has attached sculpted Cherubs also made of pure gold. 

According to the scripture, the Ark remained in the Solomon's temple until Babylonian empire destroyed it. After that time, its location was whereabouts unknown.

Some theories said that Babylonians took it. Others said that one of the final kings Josiah predicted the attacked of Babylonians and hide it proactively.
But where did he hide it? According to one midrash, he dug a hole under the wood storehouse on the Temple Mount and buried it there (Yoma 53b). Another account says that Solomon foresaw the eventual destruction of the Temple, and set aside a cave near the Dead Sea, in which Josiah eventually hid the Ark (Maimonides, Laws of the Temple, 4:1).

No one knows who keep the Ark after that time and many claimed themselves as the 'Keeper of the Ark' and they have to pass it from generation to generation.

It was believed that this Ark possessed a great power. Some sort of electricity or explosive energy will be the cause of death of those who touch it. At this moment, it really needs a brave person with a lot of faith in order to find and open it.

After 2000 years after it was last seen, many people are still interested on finding this Ark in order to hardly prove the Old Testament. This Ark was also believed to be the key for many question and mysteries of life.