Have a drink in Sean's Bar, certified by Guinness World Records in 2004 as the oldest pub in Ireland

Weigh up the claim: AD 900 by tradition, about 1725 by the official records

Walk out to the Shannon crossing in front of the pub, the reason Athlone is here

Walk up to Athlone Castle, built in 1210 to hold the same crossing

Sean's Bar on Main Street in Athlone, by the Shannon crossing, claims to have been founded in AD 900 and to be the oldest bar in Ireland, and in 2004 Guinness World Records issued it a certificate as the 'oldest pub in Ireland'. The official records disagree: the Record of Monuments and Places and the National Inventory of Architectural Heritage date the building to the 17th or 18th century — about 1725, possibly with fabric from earlier buildings — and a rental survey of 1738 calls it the Three Blackamoor Heads. When it was renovated in the 1970s, part of a back wall turned out to be wattle and wicker, and tavern tokens of uncertain age were found; they are now in the National Museum of Ireland.

Sean's Bar: The Claim to Be Ireland's Oldest Pub

Athlone and Kilbeggan

Dublin

Ten nights in a loop from Dublin to the west and back: Clonmacnoise on the Shannon, three nights in Connemara for Roundstone, the Sky Road and Killary, then Croagh Patrick and Athlone.

Connemara and the West from Dublin

Tour Athlone Castle, whose polygonal tower of 1210 is still the keep

Take a boat out onto Lough Ree from Athlone harbour at the lake's southern end

Walk Athlone's Left Bank, the old quarter between the castle and the river

Look up the lake to where Longford, Westmeath and Roscommon share its shores

Athlone grew up where the Shannon could be crossed, and that is why there is a castle here. The stone castle was built in 1210 for King John by his justiciar, John de Gray, bishop of Norwich, on a motte by the river, to hold the crossing and give the Normans a bridgehead into Connacht; it stands on or near the site of a wooden castle raised in 1129 by Tairrdelbach Ua Conchobair, and its polygonal tower of 1210, greatly altered, is still the keep. The town sits at the southern end of Lough Ree, the second-largest lake on the Shannon after Lough Derg, which forms the border between Longford and Westmeath on the east and Roscommon on the west. The old quarter, the Left Bank, is squeezed between the castle and the river.

Athlone and the Shannon's Lough Ree Shore

Find the Cross of the Scriptures and read the carved panels on it

Walk between the nine ruined churches and the two round towers

Look at the collection of over 700 early Christian graveslabs

Stand at the river and work out why the Esker Riada made this the crossroads of the country

Saint Ciarán, a Roscommon man from Rathcroghan, founded Clonmacnoise on the Shannon in 544 — and he chose the spot for a reason. This is where the Slighe Mhór, the great east–west land route, met the river after crossing the central bogs along the Esker Riada. Whoever held it controlled the crossroads of Ireland, which is why kings were buried here and why it was raided again and again. Nine ruined churches, two round towers, a castle and one of the greatest collections of carved crosses and cross-slabs in the country still stand on the riverbank.

Clonmacnoise: Where the Road Met the River

Walk among the ruins of the churches of Diarmaid's monastery, founded in 560

Find the place on the shore where legend says Medb was killed

Look back across the lough to the Longford and Roscommon shores

Inchcleraun — Inis Cloithrinn, Clothru's island — is a 143-acre island in the middle of Lough Ree, and Diarmaid the Just founded a monastery on it in 560. Between 800 and 1300 its churches were plundered and burned again and again, and they stand in ruins. Legend says Queen Medb retired here and was killed on the shore by a stone — or in another version a lump of cheese — slung from the Longford side; one point is still called Grianan Meva, Medb's sunny place. Its other name, Quaker Island, comes from a Quaker who once owned it.

Inchcleraun: Diarmaid's Monastery on Lough Ree

Walk the banks of the River Inny at Ballymahon

Read The Deserted Village in the countryside it is thought to describe

Drive down to where the Inny reaches Lough Ree

Find the Goldsmith associations around Pallas and Lissoy

Oliver Goldsmith grew up around Ballymahon on the River Inny, and local tradition, with a long line of guidebooks behind it, places The Deserted Village in this countryside — though the poem names no real village — the poem about a village emptied by enclosure and emigration, published in 1770 and still the poem people reach for on the subject of rural depopulation in these islands. The Inny runs down to Lough Ree a few miles west, and the country is very much as flat and quiet as the poem implies.

Ballymahon and the Inny: Goldsmith's Country

Walk the harbour and the lock where the canal drops into the Shannon

Find the ruins of the canal hotel that housed passengers overnight

Walk the Grand Canal towpath east from the harbour across the bog

Have a pint in one of the two pubs and watch the boats work the lock

Shannon Harbour is where the Grand Canal finally reaches the Shannon after crossing the bogs from Dublin, and for a century it was one of the busiest inland ports in Ireland — passengers and freight transferring between canal boats and river steamers, with a hotel to hold them overnight. The traffic went and the village stayed: a handful of houses, a lock, docking for boats, and two pubs. It is one of the quietest places on the whole waterway, and the junction survives largely as it was build canal junction in the country.

Shannon Harbour: Where the Grand Canal Meets the River

See the 18-metre preserved stretch of oak trackway in the humidified hall

Find out how dendrochronology dated the timbers to 148–147 BC, contemporary with the fall of Carthage

Walk the bog outside and picture the quicksand and ponds the road was built to cross

Work out why a road this wide was built here at all, in a place with nothing obvious at either end

In 1984 timbers pulled out of a Longford bog turned out to be much later than anyone had assumed — Iron Age, not Bronze Age. Dendrochronology dated the oak to late 148 or early 147 BC — the same years Rome was destroying Carthage — and what they had found was a corduroy road of split planks laid on raised rails, wide and solid enough for wheeled traffic, running at least a kilometre across what was then bog, quicksand and ponds. Locals had always called it the Danes' Road. An 18-metre stretch is preserved indoors in a humidified hall, because exposed to air the oak would simply crumble.

The Corlea Trackway: An Iron Age Road Through the Bog

See Fiddaun Castle and its bawn wall from the roadside — it stands on private farmland with no public access inside

At Coole Park, find the Autograph Tree in the walled garden and pick out WBY, GBS, SOC and Synge cut into the copper beech

Find out what Lady Gregory did here — she co-founded the Abbey with Yeats in 1904, and the house came down in 1941, leaving the garden and the tree

Walk the shore of Coole Lake and watch for the whooper swans Yeats counted — fifty-nine of them, over the winter of 1916–17

Near Gort in south Galway, two sites from different eras sit within 10km of each other. Fiddaun Castle is a mid-16th-century O'Shaughnessy tower house, best known for its unusually complete inner bawn wall, standing on private farmland. Coole Park was the estate of Lady Augusta Gregory, patron of the Irish Literary Revival; in her walled garden stands a copper beech known as the Autograph Tree, carved with the initials of W.B. Yeats, George Bernard Shaw, Sean O'Casey, J.M. Synge and others.

Fiddaun Castle and the Autograph Tree at Coole Park

See the site of the lost town from the public road, just west of Jerpoint Abbey off the R448

Find out how the 2007 Lidar survey mapped 27 houses, a mill and a tannery under a field of grass

Read the St Nicholas story and work out why a Kilkenny parish claims the bones of Santa Claus

Walk Thomastown, three kilometres north-east — the town on the Nore that outlived it

Newtown Jerpoint was founded in the 12th century where the main crossing of the Nore was carried on a toll bridge — Jerpoint means Nore bridge. At its height it had some 27 houses, a court house, a woollen mill, a tannery, a brewery and, by repute, fourteen taverns. It was not killed by the Black Death: it lasted at least into the 17th century and then faded, probably when it lost its bridge and the road was re-routed. The ruins of St Nicholas's church stand in the middle of it, and a grave slab there, carved with a cleric and the heads of two knights, is said by local tradition to cover the bones of St Nicholas of Myra, brought back from the Crusades. A Lidar survey in 2007 mapped the whole street plan under the grass. The site lies on private land at Jerpoint Park, which has closed, so for the moment there is no way in.