Walk the formal garden compartments and find the plants that should not survive this far north

Tour the house and find Castlereagh's rooms

Walk down to the shore of Strangford Lough through the estate

Find the Temple of the Winds on the high ground above the lough — it opens on summer Sundays only

Mount Stewart stands on the east shore of Strangford Lough, the Irish seat of the Stewarts, Marquesses of Londonderry — among them the 2nd Marquess, better known as Viscount Castlereagh, who was Britain's Foreign Secretary at the Congress of Vienna. The gardens are the reason to come: the mild Strangford microclimate lets things grow here that have no business surviving in Ireland, and the planting is laid out in a series of formal compartments running down to the lough.

Mount Stewart: Castlereagh's Garden on Strangford

Strangford Lough

Belfast

Four nights in a loop from Belfast: Mount Stewart, Nendrum and Castle Ward around Strangford Lough, a climb from Newcastle beach into the Mournes, then Carlingford's greenway and the Proleek Dolmen.

The Mournes and Strangford Lough from Belfast

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

Visit C.S. Lewis Square with the Narnia sculptures

Find 'Little Lea', Lewis's childhood home in Strandtown, where he grew up before his mother's death in 1908

Explore the Holywood Arches area where Lewis played

Visit St. Mark's Church, Dundela, where his grandfather was rector

Photograph the lamp post sculpture in C.S. Lewis Square, one of seven bronze Narnia sculptures unveiled in 2016

C.S. Lewis grew up at Little Lea in Strandtown, in a house with long corridors and too many books, until his mother died in 1908 and his childhood ended — the wardrobe and the grief both went into Narnia. His grandfather was rector at St Mark's, Dundela, and the Holywood Arches were his boyhood ground. C.S. Lewis Square in east Belfast holds a group of bronze Narnia sculptures, including the lamp post, which stands in east Belfast looking exactly as wrong and as right as it does in the book.

C.S. Lewis's Belfast: Little Lea and the Lamp Post

Go through the nine galleries of Titanic Belfast, from Boomtown Belfast to the wreck

Stand at the head of the Titanic and Olympic slipways and see how the building's prows line up with them

Go aboard SS Nomadic in Hamilton Dock, the last White Star Line ship in existence

Find the Thompson Graving Dock, where Titanic was finished before she left Belfast

Find the old Harland & Wolff drawing offices, and look across to Samson and Goliath

Titanic Belfast opened in 2012, a hundred years after the ship's maiden voyage, on Queen's Island, the land Harland & Wolff built Olympic, Titanic and Britannic on. The building stands 38 metres high, the height of Titanic's hull, and its prows point straight down the Titanic and Olympic slipways towards the Lagan; inside, nine galleries run from Boomtown Belfast, the city as it was in 1909–11, through the building, the launch and the sinking. Around it is the rest of the story: the Thompson Graving Dock, where Titanic was finished before she left Belfast; SS Nomadic, launched on 25 April 1911 to carry passengers out to Olympic and Titanic at Cherbourg, and now the last White Star Line ship in existence; Harland & Wolff's headquarters and drawing offices, a hotel since 2017; and Samson and Goliath, the shipyard's Krupp cranes, put up in 1974 and 1969.

Titanic Belfast: The Slipways Where She Was Built

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

Browse St George's Market, the last surviving Victorian covered market in Belfast, built 1890–1896

Walk the Cupar Way peace wall, one of the longest in Belfast and up to 8 metres high, first built in 1969 after violence on Bombay Street

Add your own message to the mural-covered wall, as thousands of visitors have done

Attend a traditional music session in the Cathedral Quarter, at pubs like the Duke of York or the John Hewitt

Belfast has a Titanic story it tells very well and several others it tells more quietly. St George's is the last Victorian covered market left in the city, built between 1890 and 1896 and still trading. Cupar Way carries one of the longest and best known of the peace walls, up to 8 metres high, first put up in 1969 after the violence on Bombay Street and still standing decades after the ceasefires, covered in messages left by visitors. And the Cathedral Quarter keeps the traditional music going in pubs like the Duke of York and the John Hewitt.

Belfast: Peace Walls, St George's Market and the Cathedral Quarter

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

Stand under the capstone and work out how 40 tonnes was lifted into place

Throw three stones onto the capstone and see whether they stay

Find the wedge tomb standing in the same field

Look across to the Cooley Mountains, the setting of the Táin Bó Cúailnge

Proleek is a portal tomb standing in the Cooley countryside — two portal stones, a backstone, and a capstone that weighs about 40 tonnes balanced on top of them. How it was raised is the question nobody has answered. Local tradition says that if you can land three stones on top of the capstone and they stay there, you get a wish, or you will be married within the year. The top of it is covered in the evidence of people trying.

The Proleek Dolmen: Land Three Stones and Make a Wish

Tour the house and walk the full 80 feet of the Pompeian Long Gallery

Find the print room, and the staircase with its Lafranchini plasterwork

Look out from the house along the axis towards the Conolly Folly

William Conolly was Speaker of the Irish House of Commons and reputedly the richest man in Ireland, and in 1722 he built Castletown to prove it — the first and largest Palladian house in the country. He died in 1729 and his widow Katherine went on entertaining lavishly there until her own death in 1752. The Long Gallery inside runs 80 feet and was decorated in the Pompeian manner in the 1770s in blue, red and gold, which is not a scheme anyone would dare now.