Behind the second veil, there was a room which is called the Holy of Holies. It measured 15 ft. (10 cubits) long, 15 ft. (10 cubits) wide, and 15 ft. (10 cubits) high. The Holy of holies was the most sacred place in the tabernacle. The ark of the covenant with its mercy seat covering was the only piece of furniture in this room.
The Holy of Holies could be entered only by the high priest, and that only on the Day of Atonement (Yom Kippur).