These altars, which escaped official documentation until the Ordnance Survey revision of 1848, represent a poignant chapter in Irish religious history when Catholic worship was severely restricted under the Penal Laws. According to J. Byrne’s testimony in the OS Revision Name Book, these were functioning Roman Catholic altars used for the celebration of Mass during times when such practices had to be conducted away from the watchful eyes of authorities.

The altars’ absence from earlier maps, including the OS Fair Plan and the first edition 6-inch map from 1834, speaks to their secretive nature. These mass rocks, or penal altars as they were known, were typically located in remote areas where lookouts could warn of approaching soldiers or officials. The faithful would gather at these outdoor sanctuaries, often before dawn or in inclement weather, risking fines, imprisonment, or worse to practise their faith. The priest would arrive separately, sometimes in disguise, carrying portable altar stones and vestments hidden beneath ordinary clothing.

Today, these six altars near Muff stand as silent witnesses to a time when religious freedom couldn’t be taken for granted. They form part of a network of penal mass stations scattered throughout Ireland, each one a testament to the resilience of communities who refused to abandon their faith despite official persecution. For visitors interested in Ireland’s complex religious history, these sites offer a tangible connection to the experiences of ordinary people who gathered in fields and glens, turning the natural landscape into sacred space when churches were denied to them.