Drumanagh
Drumanagh (Irish Droim Meánach) is a headland near the village of Loughshinny, 20 km north of Dublin, Ireland. It features a 19th-century Martello tower and a large (200,000 m²) iron age promontory fort which has produced Roman artefacts.
Some archaeologists have suggested the fort was a bridgehead for Roman military campaigns, while others suggest it was a Roman trading colony or a native Irish settlement that traded with Roman Britain.
Drumanagh is nearly 900 m long and 190 m wide. The area consists of a small peninsula defended by three rows of parallel ditches on the landward side. It is surrounded on three sides by the Irish sea, showing huge erosion that could have reduced its size to the present 44 acres (180,000 m2) and may have destroyed evidences of old Roman structures.
The site is privately owned and is a Recorded Monument, protected under the Section 12 of the National Monuments (Amendment) Act, 1994, and by a Preservation Order placed on it in 1977. Although its archaeological importance has been known since the 1950s, when ploughing turned up sherds of Roman samian ware, it has not been subject to archaeological excavation, but numerous artefacts have been dug up by illegal metal detectorists. One such collector attempted to sell a trove of Roman coins and ornaments at Sotheby's in London in the 1980s, which was impounded and deposited in the National Museum of Ireland. Since then, a legal dispute over ownership has prevented the artefacts and their provenance from being discussed publicly.
Barry Raftery and Gabriel Cooney have suggested that the fort may have been used by Gnaeus Julius Agricola, then Roman governor of Britain, for an invasion of Ireland in AD 82. The Roman historian Tacitus mentions that Agricola entertained an exiled Irish prince, thinking to use him as a pretext for a possible conquest of Ireland. Agricola, says Tacitus, "crossed in the first ship" and defeated peoples unknown to the Romans until then. He does not specify which body of water he crossed, although many scholars believe it was the Clyde or Forth; however, the rest of the chapter exclusively concerns Ireland.
...
Wikipedia