One of the largest Gothic cathedrals in the world, begun in 1386 and taking nearly five centuries to complete. The exterior is extraordinary — 135 marble spires, 3,400 statues, and a gilded copper Madonna on the tallest pinnacle. The gloomy interior is vast and worth at least 20 minutes; the rooftop terraces, reached by stairs or lift, are the main draw — you walk among the spires with views across the city and, on clear days, to the Alps.
Book rooftop tickets online to skip the queue. Arrive early for the cathedral interior; the first service is at 07:00 and the church is often empty before 09:00.