Ark of the Covenant:   The Ark of the Covenant was a rectangular box (size = 100cm x 70cm x 70cm approx) made out of acacia or shittim wood.   The Ark symbolized the presence of the living God on earth.   It contained the Ten Commandments on their original slabs; Aaron's rod which budded; and a gold urn filled with manna from Heaven.  

The Philistines captured the Ark in battle, but decided to give it back after the stone idol of their god, Dagon kept falling face down in its presence and then God afflicted them with tumours (haemorroids?).   One poor fellow named Uzzah touched the Ark to keep it from falling onto the floor, and was struck dead by God for his troubles!   The Ark went missing when Jerusalem was invaded in five hundred and eighty-six B.C. and has not been seen since.  

The Harrison Ford film, Raiders of the Lost Ark traces fictional archaeologist Indiana Jones' attempts to find it, along with the Nazis.   While it is an excellent film, it is inaccurate in many respects.   For example, the Nazis want the Ark because they say that an army which carries the Ark into battle is invincible, whereas we can see from the incident with the Philistines, that this is not the case.