All that remains of Dunseverick Castle is a small and unimpressive wall on top of a precipice that faces the ocean. You would never guess that a distinguished castle once stood on that spot and that the area was popular enough to attract a number of visits from Saint Patrick himself.
As a matter of fact, the wall that remains is the only part of the castle not destroyed by General Munro during the Irish rebellion of 1641. According to one source, the thick wall was the only part of the castle Munro's troops weren't able to demolish. I guess they weren't thinking of future tourism potential...
On the history and origin of the name Dunseverick, NorthAntrim.com says:
Dunseverick was a key ancient site in Ireland, one of the royal roads from Tara, seat of the Kings of Ireland ended here. It was originally founded by Sobairce, one of the Kings of Ireland who built a fortress here in 1525BC to rule the ancient Kingdom of Dariada, the location is named after him - Dunsobairce (Fortress of Sobairce) now Dunseverick.
On the north side of the promontory, close to the cliff edge, a well was said to exist. It was named Tubber Phadrick, which means Saint Patrick's Well. The local people would bring their children to be baptised by Patrick on his visits to the area and he would baptise them here while seated on a rock that is now said to be somewhere on the ocean floor.
There's a lot of variance as to which part of the castle actually remains today. Some say it is part of a tower, others a gatehouse and others still say it's one of the original castle walls.
It's been said that a residential tower existed on the site until it eventually collapsed into the sea in 1978.
This is by no means a complete historical timeline, but an attempt to present the events we know about in chronological order. If you've got more information to share about the history of Dunseverick, please share it in the comments.