Letterkenny

The largest town in Donegal, on the river Swilly, with what is said to be the longest main street in Ireland. It grew after partition cut the county off from its natural capital, Derry, a short way across a new border.

Near where Letterkenny stands, Godfrey O'Donnell, King of Tír Chonaill, already dying of wounds from a battle with the Normans in 1257, was carried on a litter at the head of his army and defeated O'Neill by the Swilly in 1258; he died after the battle and is buried at Conwal, where a cross-marked slab covers his grave. The town itself began as a market town of the Plantation of Ulster, on land granted to the Scot Patrick Crawford around 1609, and was launched by Sir George Marbury, who married Crawford's widow.

In October 1798 a French squadron carrying Wolfe Tone was caught off Lough Swilly and surrendered after a three-hour battle; Tone was held briefly at Laird's Hotel on the Main Street before being taken to Derry and on to Dublin. In 1824 ships of 100 tons were bringing iron, salt and colonial goods to the port of Ballyraine and taking away hides and butter.

Drawn from the History section of the Wikipedia article on Letterkenny ↗, rewritten here and adding nothing it does not say; licensed CC BY-SA 4.0.

• Beltany stone circle · stone circle · 14 km
• Raphoe Castle · castle · 13 km

Straight-line distances from the town centre, from each site's documented coordinates.

• Grianán of Aileach · The stone ring-fort of the Northern Uí Néill, 250 metres up above Lough Swilly, with terraces inside its walls for the assembled warriors of Ailech.
• Doon Well · A well beneath the Rock of Doon, where the O'Donnells were inaugurated — pilgrims still tie rags to the bushes and leave crutches they no longer need.
• Rathmullan · The pier from which the Earls sailed in September 1607 (Hugh O'Neill, Rory O'Donnell and ninety followers) never to return. Ulster's history pivots here.

All of these are pinned on the Hidden Ireland map.