St Gallen’s giant Baroque cathedral is unmissable. Designed by one Peter Thumb from Bregenz, it was completed in 1767 after just twelve years’ construction work. Easiest access is through the west door on Gallusstrasse, although it’s worth making your way through the church and out into the enclosed Klosterhof, at the heart of the complex, where you can see the full height of the extraordinary soaring east facade, dating from the 1760s. The convex facade of the apse rises above the formal lawns of the abbey, and is flanked by the two huge, concave towers rising in three sections. To the left is the palace wing, still the residence of the Bishop of St Gallen.

The interior of the cathedral (Mon–Fri 9am–6.30pm, Sat 9am–5pm, Sun noon–7pm) is vast, a broad, brightly lit white basilica with three naves and a central cupola. Although not especially high, the interior has a sense of huge depth and breadth thanks to its accomplished architecture: from the sandstone of the floor and wood of the pews, fanciful light-green stuccowork – characteristic of churches in the Konstanz region – draws your eye up the massive double-width pillars to the array of frescoes on the ceiling. The frescoes (1757–66) are almost entirely the work of one artist: Josef Wannenmacher, from Tomerdingen in southern Germany. Above the western end of the nave is a panel showing Mary sitting on a cloud surrounded by angels. The huge central cupola shows paradise, with the Holy Trinity in the centre surrounded by concentric rings of cloud on which are arrayed apostles and saints. Details throughout the rest of the cathedral are splendid: the lavish, mock-tasselled pulpit; the ornate choir screen; the richly carved walnut-wood confessionals; the intricate choir stalls; and, far away at the back of the choir, the high altar flanked by black marble columns with gold trim. The south altar features a bell brought by Gallus on his seventh-century journey from Ireland, one of the three oldest surviving bells in Europe.