In the autumn of 1306, Robert the Bruce was a fugitive king with no kingdom. His coronation had ended in disaster at the Battle of Methven; his wife and daughter were in English custody; his brothers would soon be hanged. He fled west across the sea to the Bissett family, who held Rathlin as part of the Lordship of the Glens of Antrim, and took refuge in a cave in the island's northern cliffs. The story you probably know comes from later chroniclers - the king watching a spider try and fail and try again to anchor its web, taking the lesson, returning to Scotland for the long war that would end at Bannockburn. Whether or not a spider was actually involved, Bruce did winter here, and the Bissetts paid for the hospitality. The English, who controlled the Earldom of Ulster, stripped the family of the island for their kindness to a man they considered a traitor.

On a July day in 1575, the Earl of Essex sent Francis Drake and John Norreys to Rathlin. The MacDonnells of Antrim had sent their women, children, and elderly to the island for safety while the men fought on the Ulster mainland. Drake's ships landed troops. What followed was a massacre. Hundreds of MacDonnell civilians were killed - the chroniclers wrote of bodies thrown from the cliffs, of survivors hunted through the caves. Essex reported the operation to Queen Elizabeth as a military success. The same name appears again in 1642, when Covenanter soldiers under Sir Duncan Campbell of Auchinbreck came to Rathlin to kill the Catholic MacDonalds who lived there, near kin of their clan enemies in the Scottish Highlands. They threw MacDonald women from the cliffs onto the rocks below. The death toll has been estimated at anywhere from a hundred to three thousand. Two massacres, sixty-seven years apart, both born of the politics of empire and clan and faith, both leaving the same cliffs marked in collective memory.

On 6 July 1898, an Italian inventor's employees stood at the East Lighthouse with a transmitter and aimed an invisible signal across six nautical miles of open water to Kenmara House in Ballycastle. It worked. The world's first commercial wireless telegraphy link had just been demonstrated, and Rathlin was one end of it. Guglielmo Marconi himself was not on the island - his assistants did the work - but the experiment proved that messages could be sent reliably between islands and the mainland without cables. The implications stretched from shipping insurance to global communications. Today the same crossing is still a barrier of sorts; the ferry runs from Ballycastle, weather permitting, and in heavy weather you do not get on or off the island. One hundred and twenty years after Marconi's signal, BT chose Rathlin in 2013 as the first place in the United Kingdom to trial wireless-to-the-cabinet broadband. Some places stay on the frontier.

From April through July the West Light cliffs at Rathlin host one of the largest seabird colonies in the British Isles. Common guillemots stack themselves shoulder-to-shoulder on every available ledge - some 130,000 of them. Razorbills hold the lower terraces. Kittiwakes nest in tighter clusters higher up, their cries audible from a mile away. Atlantic puffins burrow in the grass at the cliff edges and emerge with sand eels held crosswise in their beaks. The RSPB runs a viewing platform here that puts you at eye level with the birds, and on a good day the air below is so dense with wings the cliff itself appears to be moving. Northern Ireland's only breeding pair of red-billed choughs - black corvids with bright crimson beaks and legs - returned to Rathlin after the RSPB rebuilt the kind of grazed coastal grassland they need. Around 90 species nest or pass through. The Boathouse Visitors' Centre at Church Bay opens April to September, and a minibus runs from the harbour to the cliffs. From the harbour up to the lighthouse is about three miles. You can walk it.

Rathlin's population peaked at over a thousand in the nineteenth century, when the island produced kelp on a commercial scale and most people spoke Irish. The Irish language survived here until the 1950s and the 1960s, when the last native speakers died. The local dialect was unusual - closer in some ways to Scottish Gaelic than to Donegal or Mayo Irish, a reflection of the island's position as a stepping stone between the two coasts. Today about a third of islanders report some knowledge of Irish, and the language is taught again. The island elected, for some part of its history, a judge who sat on a throne of turf. Richard Branson's transatlantic balloon came down near here in 1987. HMS Drake, a torpedoed Edwardian armoured cruiser, lies on the seabed just off Church Bay, a wreck dive popular with the scuba community. The shipwrecks, the seabirds, the broadband, the language - Rathlin is small enough that you can walk most of it in a day and old enough that you can't.