https://en.wikipedia.org/wiki/Crom_CruachCrom Cruach was a god of pre-Christian Ireland. According to Christian writers, he was propitiated with human sacrifice
According to an Irish dinsenchas ("place-lore") poem in the 12th century Book of Leinster, Crom Cruach's cult image, consisting of a gold figure surrounded by twelve stone figures, stood on Magh Slécht ("the plain of prostration") in County Cavan, and was propitiated with first-born sacrifice in exchange for good yields of milk and grain.
https://en.wikipedia.org/wiki/Magh_Sl%C3%A9chtThis area has been in constant occupation from pre-4000 BC up to the present day, as is evidenced by the huge number of ancient monuments which still survive. In a small area of 3 square miles (7.8 km2) there are over 80 monuments of different types, with many others bound to be discovered by future archaeological searches. It is the densest grouping of such monuments in County Cavan and possibly in Ireland.[4]
Included are[5]
9 megalithic tombs
7 Ring barrows
3 different stone circles
9 different standing stones
2 stone-rows
5 enclosures
6 crannogs
33 ráths or souterrains
3 Early-Christian church-sites
2 Early-Christian Holy Wells
2 Bullauns
2 Medieval castles.