St Ambrose, Milan’s patron saint and one-time superstar bishop, is buried in the crypt of this red-brick cathedral, which he founded in AD 379. It’s a fitting legacy, built and rebuilt with a purposeful simplicity that is truly uplifting: the seminal Lombard Romanesque basilica. Shimmering altar mosaics and a biographical golden altarpiece (835), which once served as the cladding for the saint's sarcophagus, light up the shadowy vaulted interior.
The second chapel on the right as you enter contains frescoes by Tiepolo, while inside the treasury (€2 entry) there's some precious 5th-century sparkle. Admire the mosaic-adorned Sacello San Vittore in Ciel d’Oro, its ‘golden sky’ dome supported by winged monkeys and griffins.