Lackshinnagh Altar, recorded as a monument in the townland of Maíros in County Galway, belongs to a category of site that appears with quiet regularity across the Irish landscape: a structure designated as an altar, suggesting some form of ritual or devotional use, whether ancient or post-Reformation. In parts of the west of Ireland, outdoor altars were used for Mass during the Penal Laws period, when Catholic worship was suppressed and priests conducted services in the open air at makeshift stone structures, sometimes called Mass rocks. Whether this site belongs to that tradition, or to something older altogether, remains a question the available record does not yet answer.