Tu Hwnt i'r Bont was built in the fifteenth century as a farmhouse - a substantial one, of the kind built by yeoman farmers in the upper Conwy valley. The thick stone walls, the long low roofline, the small deep-set windows all date the building to its century. In the sixteenth century, when administrative needs caught up with rural communities, the building was repurposed as the Courthouse for the surrounding district. Sessions would have been held in the main room, with the judge sitting and litigants standing across stone-flagged floors. It is unclear how long the courthouse function lasted; for most of its history the building has been simply a substantial old house beside the bridge.

The relationship between the building and its neighbour Pont Fawr - the Great Bridge - is the heart of the site's interest. The bridge, completed in 1636, is traditionally attributed to Inigo Jones, the architect who introduced Italian classicism to England and laid out Covent Garden. Whether Jones actually designed Pont Fawr is debated - some historians point to John Jones, a more local figure - but the structure carries the attribution and the style. Three arches in cut stone span the Conwy with the proportions of a small Roman bridge. The narrow road across it can take only one car at a time; drivers wait at either end. Tu Hwnt i'r Bont sits at the western abutment, predating the bridge by more than a hundred years.

Stone farmhouses outlast empires, but they need roofs and pointing. Tu Hwnt i'r Bont fell into disrepair more than once over the centuries and was rebuilt and restored each time. By the twentieth century the building's age and setting had attracted preservation interest. The National Trust acquired it, and has since leased it to a series of operators. The first leaseholder turned it into a traditional Welsh tearoom, and a tearoom it has remained. Welsh cakes, bara brith, Glamorgan sausages, scones with cream - the food matches the building. Inside, the original beams are exposed, the floors are uneven flagstones, and the windows let in only the soft light the building's builders intended.

What put Tu Hwnt i'r Bont on every Welsh tourism brochure is the Boston ivy that covers its walls. Through summer it is dense green. In September the leaves start to turn at the edges. By mid-October the entire facade is scarlet, and from the bridge across the water it looks as if the building is on fire. The colour holds for perhaps three weeks. Photographers come from across Britain to catch it. The plant is not native; it was introduced from East Asia in the nineteenth century. But few buildings in Wales have made it so much their own, and few autumns make a stone building so obviously dressed for the season.

Tu Hwnt i'r Bont sits at 53.137 north, 3.798 west, at the western abutment of Pont Fawr in Llanrwst, about four miles south of Trefriw and twelve miles south of Conwy. From the air the bridge is a clear three-arched stone span across the wide tidal river, with the small dark form of the building hugging the western bank. Best viewed at 1,500 to 2,000 ft AGL down the Conwy valley. Nearest airports are Caernarfon (EGCK) about fifteen miles west across Snowdonia, RAF Valley (EGOV) on Anglesey, and Hawarden (EGNR) east toward Chester.