Mount Stuart — the house that tried to hold the whole universe.

The Stuarts of Bute have held land on the island since the 14th century, and the family's earlier Georgian house on the site was badly damaged by fire in 1877. Rather than restore it, the 3rd Marquess — then one of the wealthiest men in the world, thanks to the family's Cardiff docks — commissioned a wholly new house from the architect Robert Rowand Anderson, begun in 1879.

What Anderson and the Marquess produced is not a country house pretending to be a castle. It is a gothic revival cathedral to learning: a central Marble Hall rising through three storeys, arcades of Italian marble, and a vaulted ceiling of deep blue studded with the constellations and signs of the zodiac in stained glass, so that the night sky sits permanently above the stairs.

Many visitors are surprised that the grounds outshine the house for them. There are roughly 300 acres to walk: mature Victorian woodland, a shore path along the Firth of Clyde, the walled Kitchen Garden, the Wee Garden of tender exotics that thrive on the Gulf Stream air, a Rock Garden and a pinetum of enormous conifers.

Allow a full day if you can — a house tour, lunch, and then several hours outdoors. In spring the woodland is thick with bluebells and rhododendrons; in autumn the estate turns copper and the light off the water is extraordinary.

One of the best walks on the estate follows the grass beside the beech trees along the Firth of Clyde, with the water on one side, red sandstone rocks below and the mainland hills across the channel. It is level, sheltered and quiet even on busy days.

Part-way along stands a small harled church with red sandstone dressings, a Celtic cross and old flat gravestones on the lawn — a peaceful stop with the sea a few steps away.

Behind the main lawns the formal gardens are laid out in green rooms: a double avenue of pleached limes clipped into sharp blocks above bare white trunks, tall beech hedges with mown grass walks between them, and a bench at the far end that catches the afternoon sun.

Beyond the hedges the walled kitchen garden is still worked — globe artichokes in flower, ranks of vegetables, and deep late-summer borders of grasses and yellow perennials running up to the Victorian glasshouse.

Mount Stuart opens seasonally, typically from spring into autumn, with guided or self-guided access to the house at set times and longer opening for the gardens, visitor centre and café. Days and times vary year to year, so check the official site before you travel.

It sits about five miles south of Rothesay on the A844/A886 coast road — a 10-minute drive, a short local bus ride, or a pleasant cycle from the ferry pier. There is parking on site, and the visitor centre, café and much of the garden network are level and accessible.