Standing proudly within the ancient monastic complex on Scattery Island, this nearly complete round tower is one of Ireland’s most impressive examples of early medieval ecclesiastical architecture. At 26 meters tall with a base diameter of just over 5 meters, it dominates the eastern portion of the island, positioned about 20 meters west of the cathedral.

What makes this tower truly exceptional is its rare ground-level entrance—a feature found at only one other Irish round tower, at Castledermot in County Kildare. Most round towers have their doors raised several meters above ground for defensive purposes, but this entrance sits at ground level, facing east-southeast directly toward the cathedral door. The doorway itself is an architectural marvel, measuring 66 centimeters wide at the base and narrowing to 61 centimeters at the top, standing 1.8 meters high. Its lintel is supported by an ingenious corbelling system—three stones on each side creating the arch, with the gap closed by a short horizontal stone.

The tower originally had six floors, evidenced by slight offsets in the interior walls at each level, though no floors or ladders survive today. This means visitors entering through the ground-floor door can look straight up to see the full height of the structure. The windows follow a deliberate pattern, with small square-headed openings facing different directions as they ascend: north, south, southeast, west-northwest, and north again. At the very top, four slightly larger windows face the cardinal directions.

The walls, 1.34 meters thick at the base, are built from roughly coursed sandstone masonry. While most stones are small, the builders occasionally incorporated larger rectangular blocks for added strength.

The tower is nearly intact except for the very top of the cap, and though historical 19th-century photographs show a large crack running almost from top to bottom, this has since been repaired.
Archaeologists date the tower to the 10th or 11th century, placing it among the earlier examples of Irish round tower construction. Its unique ground-level entrance and excellent state of preservation make it a crucial site for understanding early Irish monastic architecture.