This ruined church adjoins the old Castle of Airth, which lies half a mile from the Forth and eight miles south-east of Stirling. The church is in part a building of considerable antiquity, dating from the transition period about the end of the twelfth or the beginning of the thirteenth century, but it has undergone many alterations, and only a small part of the early structure remains. The building as it now stands (Fig. 423) consists of a [Illustration: FIG. 423.--Airth Church. Plan.] nave and chancel, having a south wing or aisle, containing the Airth vault, and forming a transept, with a tower at the re-entering angle of the Airth aisle, and with indications of an aisle on the north side of the choir. There are also two burial vaults attached to the building, one on the north side and the other at the south-west angle, called respectively the Bruce and Elphinstone aisles. The internal length of the church is 79 feet 3 inches by about 19 feet 9 inches in breadth. The most ancient part of the church (Fig. 424) is on the north side of the nave, and consists of a bay of what has been a nave arcade, opening into a north aisle. One pillar and respond (tinted black on the Plan), with the connecting round arch, still [Illustration: FIG. 424.--Airth Church. North Arcade.] stand. The original arcade probably consisted of three bays extending to near the west gable, where there are indications, at the ground level, of what appears to have been the western respond. Whether there was originally a south arcade or not cannot now be determined, as this part has been entirely rebuilt, and all traces of the north and south aisles of the nave, if there was a south aisle, have perished. The existing north bay is 11 feet 3 inches wide, and the pillar, which is circular, is about 17 inches in diameter. It has a capital, carved with simple foliage (Fig. 425), and has a square abacus. The arch has a double set of plain arch stones, with plain soffit. The few details which survive are extremely interesting, and show this to have been a building of some importance. Behind the above bay now stands the burial aisle of the Bruces of Powfoulis. It bears over the doorway the initials of Sir James Bruce and his wife, Dame Margaret Rollox, of Duncrub, and on another part the date 1614. It seems probable that this, as well as the other aisles shown on Plan, contained, on the upper floor, the family seats or galleries of the respective houses whose arms they bear, and a burial vault beneath. [Illustration: FIG. 425.--Airth Church. Cap of Pillar.]