Find the granite slab marked PATRIC in the cathedral churchyard

Go into Down Cathedral on its hill above the town

Find the 11th-century granite font, discovered in 1927 in use as a watering trough

Walk out to Saul, where tradition says Patrick founded his first church in Ireland

A granite slab in the churchyard of Down Cathedral, cut with the name PATRIC, marks what is believed to be the burial place of Saint Patrick, who is thought to have died in 461 — though the stone itself, Mourne granite, was only put there in 1900. The cathedral around it is a 14th-century ruin restored after an Act of the Irish Parliament in 1790, and it holds an 11th-century granite font that was found being used as a cattle watering trough in 1927.

Downpatrick: The Slab They Say Patrick Is Under

Stand at Saul where the barn was given to Patrick, and where he is said to have died in 461

Walk down to where the Slaney enters Strangford Lough, the traditional landing place

Walk the four holy wells at Struell, in use since long before Patrick and still visited for cures

Look into the stone bath houses at Struell — nothing standing there now is earlier than about 1600

The claim is that when Patrick came back to Ireland in 432 the currents took his boat through the Strangford narrows and put him ashore where the Slaney runs into the lough. The local chieftain Dichu gave him a barn to hold services in — saball in Old Irish, which is why the place is called Saul — and he is said to have died at Saul on 17 March 461. A mile and a half east of Downpatrick are the four holy wells at Struell, which predate Patrick entirely and are still visited by people seeking cures; a chapel was recorded on the site in 1306, though none of the buildings standing now is earlier than about 1600.

Saul and Struell: Where Patrick Landed and Where He Bathed

Walk round the house and compare the Palladian front with the Gothic side

Find Old Castle Ward, the Wards' tower house of about 1590

Find where Winterfell was filmed on the estate

Walk out to Audley's Castle on its rock above Strangford Lough

See the Victorian laundry and the working corn mill

Castle Ward was built in the early 1760s for Bernard Ward, later 1st Viscount Bangor, and his wife Lady Anne Bligh, and it was built to both their tastes, which differed: the entrance front is classical Palladian, with columns and a pediment, and the other side is Georgian Gothic, with pointed windows, battlements and finials — and the two styles carry on inside. The Wards had bought the land in 1570, and the earliest of their houses still standing, Old Castle Ward of about 1590, is down near the shore of Strangford Lough. The estate was the filming location for Winterfell in Game of Thrones, and a tower house of 1610, built by Nicholas Ward, stands in its farmyard. It came to the National Trust in 1952, and its 820 acres of landscaped grounds hold a Victorian laundry, a saw mill and a working corn mill. A mile north-west of Strangford, Audley's Castle, a 15th-century three-storey tower house, stands on a rocky height over the lough.

Castle Ward: Two Houses in One, and Winterfell

Count brent geese on the mudflats from September through the winter

Look for common seals hauled out on the pladdies at low tide

Take the ferry across the Narrows between Strangford and Portaferry

Work out how a field of drumlins became an archipelago of seventy islands

Strangford Lough is a drowned drumlin field — the sea came in over a landscape of small rounded glacial hills and left their tops as at least seventy islands and countless pladdies. The whole lough is an Important Bird Area. Common seals haul out on the rocks, basking sharks come in, and every autumn pale-bellied brent geese arrive here from Arctic Canada in numbers that make this one of their most important wintering grounds anywhere.

Strangford Lough: Seventy Islands, Seals and Brent Geese

Start at sea level on Newcastle beach and climb toward Spelga Dam, a reservoir sitting over 370m above sea level in the heart of the Mournes

Complete the roughly 75km circuit through the Mourne Mountains, one of the toughest rides in Northern Ireland

Climb the Trassey Road toward Hare's Gap, the mountain pass between Slievenaglogh and Slieve Bearnagh

Look back west over the Deers Meadow from the top of the climb, with the sea returning on the drop into Newcastle

You start with your wheels on Newcastle beach at sea level and you climb, on one of the toughest rides in the north — a circuit of about 75km through the Mournes, taking in Spelga Dam, a reservoir sitting over 370m up in the middle of the range. The Trassey Road climbs towards Hare's Gap, the pass between Slievenaglogh and Slieve Bearnagh. From the top of the climb you look back west over the Deers Meadow and the Bann valley, with the sea coming into view again on the drop into Newcastle, having gone from the tide line to the top of the range under your own power.

Newcastle to Spelga: Sea Level to the Mournes

Walk up through the three rings of stone walls to the church at the centre

Find the rebuilt sundial and the stump of the round tower in the inner enclosure

Find out how the tide mill on the shore was dated to 619

Call into the visitor centre for the story of the site and its mill

Stop at Sketrick Castle, the tower house on the road out to Mahee

Nendrum, on Mahee Island in Strangford Lough, is the only major early monastic site in Northern Ireland whose excavation has been published in full. Tradition says St Mochaoi, who gave Mahee its name, founded it in the 5th century, and its abbots appear in the annals until 974, when the Four Masters record that the abbot Sedna Ua Demain was burned in his own house, perhaps in a Viking raid. Three dry-stone walls ring the hill, one inside the other, much of them rebuilt by H. C. Lawlor, who excavated the site between 1922 and 1924: the innermost holds a ruined church, the stump of a round tower and the graveyard, with a sundial of about the year 900 — one of the few early medieval sundials known — rebuilt from fragments found in the dig; the middle one held what the excavators called the monastic school, or workshop. On the shore below, a tide mill has been dated by its timbers to 619, the oldest excavated tide mill anywhere in the world. On the road out, Sketrick Castle guarded the causeway to the west of its own island.

Nendrum: The Island Monastery and the Oldest Tide Mill

Summit Slieve Donard (850m), the highest peak in Northern Ireland, via the Mourne Wall path from Newcastle

Follow a stretch of the Mourne Wall, 35km of dry-stone wall built 1904–1922 to enclose the Silent Valley water catchment, crossing 15 peaks

Visit Silent Valley Reservoir, built 1923–1933 by a workforce of over 1,000 men to supply Belfast's water

Camp at Tollymore Forest Park near Newcastle, the managed campsite closest to the Mourne Wall trails

The Mourne Wall is the reason to come. Between 1904 and 1922 stonemasons built about 31km of dry-stone wall over fifteen summits to enclose the Silent Valley water catchment for Belfast — a boundary wall run along the tops of a mountain range, and now the best walking route through them. It takes you over Slieve Donard at 850m, the highest ground in the north. The reservoir below was built between 1923 and 1933 by a workforce of more than a thousand men. Tollymore at Newcastle is the managed campsite nearest the trailheads.

The Mourne Wall: Fifteen Peaks and the Silent Valley

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.