An ancient foundation situated at Kirkton of Kilmahew, a half-mile (1 km) north of Cardross in Argyll and Bute, St Mahew's Chapel stands at the centre of a small cemetery. The chapel existed in 1370, but was rebuilt in 1467 by Duncan Napier of Kilmahew, who created a simple harled building, with a crow-stepped gable marking the point where the chancel roof rose above the longer roof of the nave. This new chapel was consecrated on 10th May 1467 by George Lawder, Bishop of Argyll.
The chapel had been built on the site of the cell of St. Mahew or Mochta of Louth, who died AD 535. It fell into disuse in the early 17th century, and the nave became a school in 1640. Robert Napier of Kilmahew retained the chancel as a family burial vault. The building was completely abandoned in 1846, when the school transferred to new premises.
The Kilmahew Estate was acquired by the Roman Catholic Church (Archdiocese of Glasgow) in 1948, who built a seminary nearby. They commissioned Ian G. Lindsay and Partners of Edinburgh to restore the chapel in 1955, extending it to the west to support a modest belfry and building a small vestry on the northern end.
During this work the Mediaeval baptismal font was discovered, together with the upper part of a standing stone inscribed with a cross, probably dating to the 6th century, and a 9th or 10th century tomb carved with a Celtic interlaced pattern. Thereafter the chapel was used by St Peter's Seminary for worship, with the Most Reverend Donald A. Campbell, Archbishop of Glasgow, celebrating the first mass here for four centuries on 22nd May 1955.