Walk out to the Irish Yew, about a mile south-east of the house in the old 18th-century gardens, and stand under the parent of almost every one in the world

Work out why a tree that cannot set viable seed is now on every continent

Tour the 18th-century house built by the Cole family, Earls of Enniskillen

Walk the estate towards Cuilcagh, where the two saplings were found in 1767

In 1767 a farmer called George Willis found two odd yew saplings on Cuilcagh mountain — upright, columnar, nothing like a normal yew. One died. The other was planted at Florence Court and is still alive. Because the Irish Yew cannot be grown from seed and propagates only from cuttings, almost every Irish Yew in every graveyard and garden in the world is a cutting from a cutting from that one tree. The house it stands behind was built by the Cole family and named for Florence Bourchier Wrey, who died in 1718.

Florence Court: The Mother of Every Irish Yew

Take the underground boat journey along the Cladagh River when water levels allow it — the tour runs about 75 minutes either way

Walk the show cave passages beside the Owenbrean River, in a system first explored in 1895

Note the cave's full surveyed length — 11.5km, the longest known in Northern Ireland, of which the tour covers a small part

Book ahead — Marble Arch Caves tours are timed and can sell out in peak season

Marble Arch was first explored in 1895 by Édouard-Alfred Martel and the Dublin naturalist Lyster Jameson, and when the underground water levels allow, the tour still starts the way the cave does — by boat along the underground Cladagh River. Otherwise you walk the passages beside the Owenbrean under the Fermanagh hills. The whole trip takes about 75 minutes and covers a small part of the 11.5km surveyed so far, the longest known cave system in Northern Ireland. Tours are timed and sell out in season, so book before you drive out.

Marble Arch Caves: The Cladagh River Boat Journey

Walk the boardwalk out across the blanket bog to the foot of the mountain

Climb the stepped section to the viewing platform at the top of the boardwalk

Look out over the Fermanagh lakeland and into Cavan from the platform

Find out why the boardwalk was built in the first place — to stop walkers destroying the bog

The Cuilcagh Boardwalk Trail was built in 2015 for an unglamorous reason: walkers were destroying the blanket bog underfoot, so a raised timber walkway was laid across it to protect the peat. Then it went viral, got nicknamed the Stairway to Heaven, and started drawing far more people than anyone planned for. The walk itself is genuinely good — a long approach across open bog, then a steep flight of steps onto the cliff-edged summit plateau of hard Lackagh Sandstone, with the Fermanagh lakeland spread out below.

Cuilcagh: The Stairway to Heaven Over the Blanket Bog

Walk the Calf House Dolmen Trail from the interpretative centre

Find the Giant's Leap wedge tomb, one of the most intact in Ireland

Find the erratic boulders the ice left on the plateau

Look for the boulders carved with prehistoric rock art

Cavan Burren Park sits on a limestone plateau about 295 metres up under Cuilcagh Mountain, in the Cuilcagh Lakelands Geopark, and it is one of the finest prehistoric landscapes in Ireland. It holds wedge and portal tombs going back to the Neolithic — among them the Calf House Dolmen, the Tullygobbin wedge tomb and the Giant's Leap wedge tomb, one of the most intact wedge tombs on the island — with cist graves, relict field walls, hut sites, a promontory fort and boulders carved with prehistoric rock art. The ice left huge erratic boulders scattered across the plateau, and the Giant's Leap is the bed of a vanished river. Five trails run from the interpretative centre; entry is free and it is open all year.

Cavan Burren: Tombs and Erratics on the Limestone

Find the Watergate, the twin-turreted tower Cole added to the river front in 1609

Go through the Fermanagh County Museum inside the castle

See the Inniskillings regimental collections

Work out why an island where the Erne narrows was worth a castle from 1428 onwards

Hugh Maguire built a castle at Enniskillen in 1428 on the island where the Erne narrows, controlling the only crossing between the upper and lower lough — which is why the town is there at all. The Coles remodelled it after the Plantation and added the Watergate, the twin-turreted riverside tower, in 1609. It was besieged unsuccessfully by Rory Maguire in the 1641 rebellion while sheltering Protestant settlers, and it now holds the Fermanagh County Museum and the regimental museums of the Inniskillings.

Enniskillen Castle: The Maguire Watergate

Tour the house and look at how exactly Wyatt's neoclassical proportions are held

Look at the Portland stone façades and the Ionic portico, and think about shipping that stone from Dorset in the 1790s

Walk the 1,200-acre wooded estate and the lough shore

See the state bedroom prepared for a royal visit that never happened

Armar Lowry-Corry, 1st Earl Belmore, built Castle Coole between 1789 and 1798 as a summer retreat, and spared nothing doing it: James Wyatt designed it, the façades are faced in Portland stone brought from Dorset, and the portico carries sober Ionic capitals. It is about as pure a piece of neoclassical architecture as exists in Ireland, standing in 1,200 acres of wooded estate that the family had held since the Belfast merchant John Corry bought it in 1656.

Castle Coole: Wyatt's Portland Stone Palace

Visit the Shannon Pot - source of the mighty River Shannon

Walk part of the Cavan Way trail that passes the Shannon Pot

Find the legend of Síonnan and the Salmon of Wisdom told at the Shannon Pot, said to be the river's mythical origin

Drive round to the Fermanagh side for the Cuilcagh boardwalk, the Stairway to Heaven — a half-day walk in itself

The Shannon runs 360km and is the longest river in the British Isles, and it begins as a dark pool about sixteen metres across on the slope of Cuilcagh. The legend attached to it is older than the measurement: tradition says Sionann came to the pool against warning, the waters rose and drowned her, and the river carries her name ever since. The Cavan Way passes the pot. On the far side of the mountain, a half-hour drive round through Fermanagh, is the Cuilcagh boardwalk — the Stairway to Heaven.

The Shannon Pot: Where Ireland's Longest River Starts

Walk out to Mussenden Temple on the cliff edge above Downhill Strand

See how close the cliff edge comes to the walls, and where the 1997 stabilisation work holds it back

Walk the ruins of Downhill House, the Earl Bishop's mansion behind the temple

Go down onto Downhill Strand and look back up at the temple from the beach

Frederick Hervey, 4th Earl of Bristol and Church of Ireland Bishop of Derry from 1768 to 1803, built a small circular temple on the cliff edge above Downhill Strand in 1785 and kept his library in it. It was once possible to drive a carriage the whole way around the building. It is not now — the Atlantic ate the cliff in so close that the National Trust had to stabilise it in 1997 to stop the building being lost, which is the only reason it is still standing there.

Mussenden Temple: A Library on the Edge of a Cliff

Find the Caldragh graveyard on Boa Island and walk in among the stones

Look at both faces of the two-sided Janus figure and the hollow cut in its head

Find the smaller Lustymore figure, moved here from the neighbouring island in 1939

Decide for yourself whether these are pre-Christian or early Christian — nobody else has settled it

In the old Caldragh graveyard on Boa Island stand two carved stone figures that nobody can confidently explain. The larger is two-sided — a face on the front and another on the back, arms crossed, hollow on top — and is usually called the Janus figure, though whether it is pre-Christian, early Christian or something in between is still argued. The smaller one was carried over from Lustymore Island in 1939. They sit in an overgrown graveyard on a low island in Lower Lough Erne, with no ticket, no guide and no explanation.