The Ark of the Covenant was a great shrine that contained the tablets of the Ten Commandments that were received from God by Moses on Sinai. According to the Bible, the Ark was made of acacia wood and overlaid with gold. It measured 1.15 m long, 0.7 m wide and 0.7 m high and was carried by two long bars, also made of gold-plated acacia wood. The Ark was guarded by cherubims that "spread forth their two wings over of the place of the ark" (I Kings 8:7).

At some point, the Ark disappeared from Jerusalem. The mystery of what became of such an important and sacred artifact continues to fascinate archaeologists, historians and believers alike. There are no shortage of theories as to its fate and current location, which include a Jerusalem tunnel and the top of Mt. Nebo in Jordan.

To Ethiopian Christians and Jews, the location of the Ark of the Covenant is no mystery. According to the Ethiopian royal chronicles, the Ark left Jerusalem much earlier than generally thought - in the days of King Solomon - and went to Ethiopia by the hand of Menelik, the son of King Solomon and the Queen of Sheba. St. Mary of Zion claims to contain the original Ark of the Covenant. According to tradition, the Ark came to Ethiopia with Menelik I after visiting his father King Solomon. Only the guardian monk may view the Ark,in accordance with the Biblical accounts of the dangers of doing so for non-Kohanim. This lack of accessibility, and questions about the account as a whole, has led foreign scholars to express doubt about the veracity of the claim. The guardian monk is appointed for life by his predecessor before the predecessor dies. If the incumbent guardian dies without naming a successor, then the monks of the monastery hold an election to select the new guardian. The guardian then is confined to the chapel of the Ark of the Covenant for the rest of his life, praying before it and offering incense. Agreeing with ancient sources about a magnificent light emitted from the Ark, the History Channel in a 2008 special claimed that many of the guardian monks have died in short time, mostly with cataracts having formed in their eyes.

This theory was popularized outside of Ethiopia through a 1990s book by British journalist Graham Hancock entitled The Sign and the Seal: The Quest for the Lost Ark of the Covenant. Hancock argues that after the Ark was brought to Ethiopia by Menelik, it was kept there for 800 years by a Judaic cult. Then it was seized by the Knights Templar, who thought that it was the Holy Grail. The Knights converted the Jews, who then kept the Ark in a great church.
The Ark of the Covenant was long enshrined in the Old Church of St. Mary of Zion at Axum, constructed specially for the purpose by Emperor Haile Selassie in the early 1960s. Today it is housed in a small chapel or Treasury building next door to the church.