Dubrovnik Cathedral

Where it sits. The Cathedral of the Assumption of the Virgin Mary occupies a small square just south of the Rector's Palace, close enough to the sea wall that the light inside changes with the water. It is a compact Baroque building with a broad triple-arched façade, a shallow dome over the crossing and almost no space around it, which is why photographs rarely do it justice: the only viewpoints that take in the whole exterior are from the city walls above or from the alley angles that cut it in half.

Three cathedrals, one site. What stands here is the third church on the spot, built between 1671 and 1713 after the earthquake of 6 April 1667 destroyed its predecessor along with most of the city. The design came from Andrea Buffalini of Urbino, and construction was supervised in turn by Paolo Andreotti of Genoa and later Croatian masters, with the consecration in 1713. Beneath the present floor lie the other two. Excavations begun in 1981, prompted by structural work after an earthquake, uncovered the Romanesque cathedral of the twelfth and thirteenth centuries and, below it, a Byzantine basilica of roughly the seventh century, with fragments of screens, column bases and burials. That undercroft is now open and is the most historically interesting part of the building. The Romanesque cathedral carried a durable legend: that Richard the Lionheart, shipwrecked near Lokrum in 1192 while returning from the Third Crusade, vowed to build a church where he came ashore and was persuaded to endow it here instead. The story is unprovable and probably embroidered, but it stuck.

The treasury. The cathedral's treasury is the reason to buy the small extra ticket. It holds well over a hundred reliquaries in gold and silver from the eleventh century onward, the great set of them made for the cult of St Blaise, the city's patron. The most striking is the head reliquary, a Byzantine enamelled crown of the eleventh century adapted to hold the skull; alongside it are silver-gilt casings for his arms and one leg, worked in a Ragusan goldsmith's idiom that persisted for centuries. Access was controlled by three separate locks whose keys were held by three different officials. Above the main altar hangs a large polyptych of the Assumption attributed to Titian and his workshop, painted around the middle of the sixteenth century and one of the few major works to survive 1667.

On screen — the correction. This is the building most frequently and most wrongly identified as the Great Sept of Baelor from Game of Thrones. No part of the series was filmed here. The Great Sept was a set constructed at Titanic Studios in Belfast, and its domed exterior, the one that ends the sixth season in green fire, was a digital creation with no physical original anywhere in Croatia. The Dubrovnik location used for the exterior of the sept in the fifth season is the baroque Jesuit staircase a few hundred metres uphill, where Cersei begins her walk of atonement. Tour guides conflate the two constantly, partly because the cathedral is the nearest large domed church to that staircase. The cathedral deserves an hour on its own account, but not for that reason.

What you actually see today. The interior is restrained by Baroque standards — a Latin cross, pale stone, a bright and rather cool light — and its side chapels hold work by Italian and Dalmatian painters of the sixteenth to eighteenth centuries. Services are held daily and the building is in constant parish use rather than being a ticketed monument; visitors are asked to cover shoulders and knees and to stay out of the nave during Mass. On 3 February, the feast of St Blaise, the reliquaries are carried out and processed around the old town behind guild banners, an unbroken civic ritual that predates the present building by six hundred years and is recognised as intangible cultural heritage.

Getting there and timing. The cathedral is two minutes from Luža Square, at the end of the short street that runs past the Rector's Palace. Entry to the church is free; the treasury and the undercroft carry small charges. There is a shallow step at the main door and the interior is level, so partial wheelchair access is possible, but the undercroft is reached by stairs. Early morning and the hour before evening Mass are the quietest; between eleven and three the small square outside can be almost impassable when several cruise groups converge on it at once.