Circle 1 is located directly across the road from the visitor's centre. There are 35 boulders in a complete circle, surrounding a raised platform or tertre. The circle measures 12 meters in diameter, and has a smaller inner circle or setting which is 8 meters in diameter. This feature is found at a number of sites in Carrowmore, but this is the best example that can be seen today; circular settings were also found at Knowth under the smaller satellite monuments.
The stones at Circle 1 originally stood upright in a complete ring. Today, most of the stones have fallen over and are lying prone. Drystone packing was found under some of the boulders on the west side, which was placed there to keep the tops of the circle stones level. Stone packings were noted at several of the Carrowmore circles.
Borlase's report, 1895
No. 1 (dolmen-circle), " the most western of the chain of circles north of the road leading from Seafield to Sligo."
"This forms an elevated platform, and has an inner circle of smaller stones with a broken cromleac in the centre. The stones of the outer circle, which is 40 feet in diameter, are of very large size, and 35 in number; but two of them have fallen from their places. Bones were found beneath the cromleac." - Petrie.
"The elevated platform is several feet above the surface of the surrounding soil, rising as much as 6 feet to the west. The outer circle is 43 feet in diameter, and is formed of 36 stones. There were 25 of the stones of the inner circle. One support of the cromleac was in situ.
An excavation was made to the west of this, and a few inches beneath the surface some greyish-white, and seemingly highly calcined fragments of bone, were dug up. Dr. Frazer pronounced them to be all human, and identified parts of a skull, and thigh and leg bones. With the calcined remains was discovered the upper portion of a rude pin seemingly made of horn, in several fragments. A larger fragment may have formed part of a larger pin or small dagger. There was a semicircular piece of a bone object, and two small portions of an urn." - Wood-Martin.