The term "Kodesh HaKodashim," or "Holy of Holies," refers to the innermost sanctum of the ancient Temple in Jerusalem. It was considered the most sacred space, where the presence of God was believed to dwell. Only the High Priest could enter this area, and only on Yom Kippur, the Day of Atonement. The Kodesh HaKodashim housed the Ark of the Covenant, which contained the tablets of the Ten Commandments. This space was separated from the rest of the temple by a thick curtain, symbolizing the barrier between the divine and the earthly realm.