An apse - a projecting part of a building - usually a semi-circular part of a church - is an architectural feature found predominantly in Maryland.

Henry H. Saylor, long-time editor of the Journal of the American Institute of Architects, defines it as "the eastern or altar end of a basilica or church, usually semi-circular in plan and vaulted with a half-dome."

Apses are found in at least two locations in South Carolina and one is known in Pennsylvania. Wherever, it appears, the church was usually built before the Revolutionary War.

Old Trinity Church, on Rte. 16 west of Cambridge, Md., is a perfect example. This is generally considered to be Maryland's oldest church, erected about 1680. Although tiny, it has a classic example of an apse at its east end.

St. Paul's Church west of Chestertown, Md., erected in 1715, also has an apse at the east. It is the oldest church in the state to have held regular services. South of St. Paul's in the charming town of Church Hill, Md., venerable St. Luke's Church has an eastern apse, as does St. Andrew's in Princess Anne.

Pungoteague Church in Accomack County, Va., has an apse, but its appearance is so far removed from the Maryland churches that the structure has become known as the Ace of Clubs Church.