Hellnahellir, the largest man-made cave in Iceland. Constructed by Irish monks who settled there before the vikings, circa 900 AD.

The Landnámabók describes how the first #vikings to land in Iceland met 'Papar' - a name given to Irish monks.

The first observations of sea ice came from 8th century Irish monks in Iceland. Scientists still make use of their notes today:

Cross sculptures made by Irish monks in their monastic caves on the Westman Islands, #Iceland - 9th century. Some 200 such caves exist.

Icelandic names of Irish origin: Njál (Niall) Brján (Brian), Kjartan (McCartan), Kormakr (Cormac), Kjaran (Ciaran).

Hibernia is the Roman name for Ireland, meaning 'the land of winter'. They saw it as an inhospitable land at the edge of the known world.

In the Iliad, Homer described Ireland as "a land of fog and gloom.. beyond it the Sea of Death, where Hell begins." #Ireland #Homer

Ireland was well-connected to the cultures of the ancient world: Tin was imported from Britain, amber from the Baltic, wax from the Pyrenees.

Ancient Ireland's most important export was hide/leather, used by the Roman army. Thus the highest grade of freeman was a cattleman (boaire)

The Romans accessed all parts of Ireland via special trading sites known as Emporia. Roman coins, pottery, jewelry were found at #Newgrange.

A small copper figure of Lares, found in the Boyne, Co Meath. The deity was believed to protect the inhabitants of the Roman household. #Meath

Ptolemy's map of ancient #Ireland and her peoples. It was made in 150AD using the geographical knowledge of Mediterranean traders.

The Greek geographer and explorer, Pytheas, passed through what is now Belfast on his famous expedition to Thule in the far north. #Belfast

Hook Lighthouse in Co. Wexford, #Ireland - The oldest operational lighthouse in the world, its tower dates from the 12th century.

Deireadh Fómhair (October) is the "End of Harvest" in Ireland. In the Gaelic calendar the new year begins on the 1st of Samhain (November).

Oct 31: Celtic holiday of Samhain, or "summer's end", is celebrated; a night where the dead are unleashed from the Otherworld to roam ours.

Samhain is a festival of both life & death: One's ancestors are honoured around communal fires, and the incoming year is celebrated joyfully.

A #poem by medieval monk Colman the Irishman - Written for his departing friend; who, homesick, is bound for #Ireland.