Work on building the Chapel started in 1763.
The original intension had been for the garrison to attend the local kirk at Kirkton of Ardersier, close beside the road to Nairn. The minister of Kirkton served as the fort chaplain until 1777, when the duty passed to the minister of Ardersier. The handsome building is thought to have been designed by one of the Adam brothers, perhaps Robert himself. The exterior has a polygonal chancel at the east end and a squat battlemented west tower. The central nave has flanking rounded stair towers.