St. Cronan's Church, church in Ireland

St. Cronan's Church is a 10th-century stone church in Tuamgraney, built from roughly coursed sandstone sourced within 3 km. It is a Type 2 unicameral mortared pre-Romanesque church with a deep anta of 0.59 metres and rare ashlar walling in the chancel. It retains its original doorway, whose lintel and architrave are carved.

A wooden monastery existed on the site before 550 CE, probably founded by Saint Cronan, and survived Viking looting in 886 and 949. The present stone church was built by Cormac ua Cillín around 949–964; it was repaired in 1012 by Brian Boru, High King of Ireland, whose brother Marcán was abbot here, and extended in the 12th century.

Inside the church is a carved Romanesque sandstone head, originally set in the eastern gable's external wall and covered in plaster until its restoration in 1990. It is known locally as Gráinne and is thought to be the origin of the placename Tuamgraney; others say it represents St. Cronan himself.

The church is an active Church of Ireland place of worship, so visits fit around services rather than fixed opening seasons. The East Clare Heritage Centre held a licence on the building from 1992 until 2014, when the Dean declined to renew it so the church could be used exclusively for worship. The graveyard, where both Church of Ireland and Roman Catholic burials took place, lies outside the church.

The claim to continuous use applies to Ireland alone: it is the oldest church in continuous use in Ireland. The building also holds a three-light stained glass window by Alfred E. Child, titled The Ascension, commissioned in 1906 by a Miss Ivers in memory of her parents and moved here in 1990 after being vandalised at Kilfinaghta.