Sheemor is a limestone hum near Leitrim Village in the middle of Co Leitrim. The summit of the hill rears up above the surrounding plain to a height of 178 meters above sea level. From a distance the hill looks rather like a large altar, as the largest and centre-most of the three cairns on the flat top has a large modern Christian cross at the highest point. As if that wasn't strange enough, the cross is illuminated at night, and seems to float in the sky over the dark countryside!
The cairn is about 22 meters in diameter and 5 - 6 meters high, and as far as we know, has never been opened. The cairn is built with chunks of limestone quarried close by. The cross was erected in 1950 to mark the Catholic definition of the dogma of the assumption.
The two smaller cairns on the left and right are quite disturbed, and chamber or passage-slabs can be seen amid the stones, and the sites obviously date from the Neolithic, over 5,000 years ago. The large cairn, though much disturbed by the cross, remains unopened. This site lies between Carrowkeel and Loughcrew, Knocknarea.
From an archaeo-astronomers perspective, the Sheemor - Knocknarea alignment is highly signifigant. The winter solstice sunrise, viewed from Queen Maeve's Cairn, rises over Sheemor.
Standing at the cross on Sheemor, the summer solstice sunset drops behind Knocknarea. The cairn called Shee Lugh on Moytura is between these two sites. This is more evidence of large-scale surveying in Neolithic Ireland.