The Duomo might have all the glory but Sant' Ambrogio is considered the 'true' church of Milan. It was founded in ad 386 by the bishop Ambrose, who was canonized shortly after his death in 397 and is now Milan's patron saint. With multiple phases of construction over nearly two millennia, any trace of the church's 4th-century origins has all but gone, not least after World War II bombing and Napoleonic suppression, which saw its monastery converted into a military hospital in 1797.
In beautiful red brick, it remains the most important example of Lombardy Romanesque architecture, originally built to commemorate two Christian martyrs, Gervasius and Protasius. Their rather ghoulish skeletons, dressed in white and gold ceremonial robes, now flank Saint Ambrose's in the 10th-century crypt.
On 7 December is the Feast of Sant' Ambrogio, Milan's patron saint's day, which is centred on this basilica. It's the city's biggest festival and is marked with a spirited street fair in the piazza and flowing vin brulè (mulled wine).