it has a causeway connecting it to the mainland at Tooban, south of Fahan. Lough Swilly is a fjord-like lough, and was of strategic importance for many years to the British Empire as a deep-water harbour. It is also famous as the departure point of the Flight of the Earls. Lough Foyle is important as the entrance to the river Foyle, and the city of Derry, but is much shallower than Lough Swilly, and requires the use of a guide boat to guide ships to and from Londonderry Port. A large area of land, most of which now forms part of Grianán Farm, one of the largest farms in Ireland, was reclaimed from a shallow area of Lough Swilly, stretching from the village of Burnfoot to Bridgend and Burt. The outline of this land is plainly visible due to its flatness, showing a marked contrast to the more mountainous area surrounding it. History Ptolemy's Geography (2nd century) described a point called Ουεννικνιον (Wenniknion, perhaps from *wen- "friends") which probably referred to Inishowen. Predating the formation of County Donegal by centuries, the area was named Inis Eoghain (the Island of Eoghan) after Eógan mac Néill, son of Niall of the Nine Hostages (Niall Naoigeallach, a High King of Ireland), whose name was also used for Tyrone (Irish: Tír Eoghain). Inis Eoghain is also the ancient homeland of the Meic Lochlainn (descended from the tribe of Eoghan), a clan that grew so formidable that they eventually came under siege by a Limerick King, who came north to Aileach, and ordered the destruction of Aileach fort, and that each soldier was to carry away a stone from the fort in order to prevent its rebuilding. Later, after the decline of the Meic Lochlainn, the Norman Earldom of Ulster expanded into Inishowen, founding Greencastle in the process. After the Bruce invasion in the early 14th century, the Ó Dochartaigh clan (descended from the tribe of Conaill), gradually conquered it as they lost their own homeland in the Laggan, a district in the east of Tír Conaill. Inishowen has many historical monuments, dating back to early settlements, including the ruins of several castles, and the fort at Grianán Aileach. The ancient Grianán Ailigh fort at Burt was the one-time seat of the High Kings of Ireland, including both High Kings of the Meic Lochlainn, who held power in Inis Eoghain for many centuries. It was