🇮🇪 Ireland · Earthwork
Grianan of Aileach
Iron Age to Early Medieval (c.1000 BCE–1100 CE) · Iron Age Gaelic → Early Medieval Uí Néill
Donegal hilltop royal cashel (23.5 m diameter) on Greenan Mountain — northern Uí Néill kingship inauguration fort.
🇮🇪 Ireland · Earthwork
Dún Aonghasa
Late Bronze Age to Early Medieval (c.1100 BCE–800 CE) · Atlantic Iron Age / Early Medieval Gaelic
Cliff-edge triple stone fort on Inishmore (6 ha) with massive chevaux-de-frise of jagged limestone — Ireland's most dramatic hillfort.
🇮🇪 Ireland · Earthwork
Cahercommaun Triple Ringfort
Early Medieval (8th–14th century CE) over Late Neolithic traces · Gaelic Early Medieval (Eoghanacht / Dalcassian)
Triple-walled Burren cashel on cliff spur above Carran — Early Medieval high-status ringfort with 13 house platforms.
🇸🇪 Sweden · Earthwork
Eketorp Ringfort — Öland
Iron Age to Medieval (c.400–1300 CE) · Scandinavian Migration/Vendel and Medieval Gotlandic–Swedish
Eketorp, on southeastern Öland's Stora Alvaret limestone plain, is the only fully excavated of Öland's 19 Iron Age ringforts, a concentric limestone-walled fortress 70 m diameter with 53…
🇸🇪 Sweden · Earthwork
Stavgard Ringfort (Gotland)
Migration Period to Vendel Period (c.400–800 CE) · Gotlandic Iron Age
Pre-Viking ringfort (fornborg) on Gotland's southeast, circular limestone wall 80–100 m diameter enclosing 0.5 ha, with inner house terraces and Iron Age ceramics.