The inner room of the tabernacle and temple where they kept the ark of the covenant. The ark was a gold-covered wooden box that held important holy items, including the stone tablets with the Ten Commandments (Exodus 25:10–22).
This room was the most holy space in Israelite worship. Only the high priest could enter it, and only once each year on the Day of Atonement (Leviticus 16). Before entering, the high priest had to perform special cleansing rituals.
In the temple, the most holy place was separated from the rest of the building by a thick curtain. This curtain tore from top to bottom when Jesus died (Matthew 27:51).
The room was also called the "holy of holies," which means "the holiest place."