Slievemore also shows evidence of early Christian settlement in the vicinity of the graveyard and Kildamhnait, on the south east coast of Achill, is named after St Damhnait, or Dymphna, who founded a church there in the 16th century.

Dymphna fled to Achill to escape her tyrannical father and established her church on this site. There is also a holy well just outside the graveyard. The present church was built in the 1700's and the graveyard contains memorials to the victims of two of Achill's greatest tragedies, the Kirchtilloch Fire and the Clew Bay Drowning.

Kildamhnait Castle is adjacent to the church and graveyard. It is a classic tower house associated with the O'Malley Clan, who were once a ruling family of Achill and attributed to the famous Pirate Queen Grace O’Malley (1530-1603), but it was built one hundred years before her time c. 1429. Grace O'Malley was a local sea pirate who is reputed to have met with Queen Elizabeth I during her lifetime.

Tower Houses were home of strong farmers or local lords.

Kildamhnait Tower House is a rectangular three-storey battlemented building, 12 metres high with a small walled enclosure on the West side. Narrow windows provided light for the interior rooms and protected from attackers. There was a winding stair leading to the floors above. On the North side over the doorway the remains of machicolation can be seen. From this buttresses the inhabitants poured boiling oil or other unpleasant items upon the heads of their enemies.

The Tower House was strategically located as a sentinel over the Sound protecting Achill against attacks from Blacksod Bay to the North and from Clew Bay to the South.