From Belfast: Carrickfergus Castle, Dunluce & Giant's Causeway

Carrickfergus Castle was built by John de Courcy, the Anglo-Norman adventurer who invaded and conquered Ulster in 1177 — one of the most audacious individual military campaigns in medieval Irish history. De Courcy arrived from England with a small force, defeated the Ulster king at the Battle of Down, and carved out a personal kingdom in northeast Ireland, building Carrickfergus as his headquarters on the shore of Belfast Lough. The castle's keep — four storeys of grey basalt, still complete with its original battlements — is one of the finest Norman keeps in the British Isles. The guide covers the castle's remarkable history: King John of England (the Magna Carta king) besieged it in 1210; Edward Bruce of Scotland seized it in 1316 during the Bruce invasion of Ireland; William III landed nearby in 1690 on his way to the Battle of the Boyne. The castle was in military use until 1928.

The Antrim Coastal Road, built in the 1830s as a famine relief project, follows the basalt cliffs north from Larne through a landscape of waterfalls, raised beaches and ruined abbeys. The guide covers the geological story — the Antrim plateau is one of the largest basalt formations in the world, created by the same volcanic episode that formed the Giant's Causeway 60 million years ago — and the medieval history of the Glens of Antrim, which were controlled by the MacDonnell clan (later the Earls of Antrim) who imported Scottish gallowglass warriors from the Western Isles to fight the English. Pass the ruins of Glenarm Castle, the Layde Church ruins where the MacDonnells are buried, and the Dark Hedges — the beech tree avenue filmed as the King's Road in Game of Thrones.

Dunluce Castle stands on a detached basalt sea stack at the edge of the Antrim plateau, connected to the mainland by a narrow rock bridge over a 30-metre drop to the cave and sea below. The castle was the seat of the MacDonnell clan — the most powerful lords of northeast Ireland — and was built in the 13th century, expanded in the 15th and 16th centuries, and finally abandoned in the late 17th century after the clan's power collapsed. The most famous incident in the castle's history: in 1639, during a dinner party, the castle's kitchen — built overhanging the sea cave below — collapsed into the cave, taking an unknown number of kitchen staff with it. The Countess of Antrim reportedly never returned to Dunluce after this. The ruins are the most dramatically positioned in Ireland: the outer ward walls drop vertically into the sea cave, the inner ward towers overlook the Atlantic, and the entire basalt stack is isolated from the mainland on three sides by the sea.

The Giant's Causeway — UNESCO World Heritage Site — is a formation of approximately 40,000 interlocking basalt columns stepping down from the cliff face into the North Atlantic. The columns were formed 60 million years ago when a massive lava flow cooled and contracted into regular hexagonal shapes with extraordinary geometric precision: most are hexagonal, but some have four, five, seven or eight sides. The guide covers both the geological explanation (Paleocene volcanic activity) and the legend: the Irish giant Finn MacCool supposedly built the causeway as a path to Scotland so he could fight his Scottish rival Benandonner — who was so terrified when he saw Finn's size that he fled back across the sea, tearing up the causeway behind him.