In church architecture, sedilia (plural of Latin sedīle, "seat") are seats, usually made of stone, found on the liturgical south side of an altar, often in the chancel, for use during Mass for the officiating priest and his assistants, the deacon and sub-deacon.
Not all sedilia are stone; there is a timber one thought to be 15th century in St Nicholas' Church at Rodmersham in Kent.
During certain sections of the liturgy, especially Gloria and Credo, the clergy sat in the three-seater (also Levite's seat, bench, chair,[2] celebrant's chair) when the Mass was celebrated as the Levitical office of priest, deacon and subdeacon.
Since the Second Vatican Council, celebrating the Mass as a "Levite ministry" has only been customary in the extraordinary form of the Roman Rite.
Here the oldest, niche-shaped three seats made of stone in the bond of the chancel wall are still preserved.