Milan's most famous mural, Leonardo da Vinci’s The Last Supper is hidden away on a wall of the refectory adjoining the Basilica di Santa Maria delle Grazie. Depicting Christ and his disciples at the dramatic moment when Christ reveals he's aware of his betrayal, it's a masterful psychological study and one of the world's most iconic images. To see it you must book in advance or sign up for a guided city tour.

When Leonardo was at work on the masterpiece, a star-struck monk noted that he would sometimes arrive in the morning, stare at the previous day's efforts, then promptly finish for the day. Your visit will be similarly brief (15 minutes to be exact), but the baggage of a thousand dodgy reproductions are quickly shed once standing face to face with the luminous work itself.

Centuries of damage have left the mural in a fragile state despite 22 years of restoration, which was completed in 1999. Da Vinci himself is partly to blame: his experimental mix of oil and tempera was applied between 1495 and 1498, rather than within a week as is typical of fresco techniques. The Dominicans didn't help matters when in 1652 they raised the refectory floor, hacking off a lower section of the scene, including Jesus' feet. But the most damage was caused by restorers in the 19th century, whose use of alcohol and cotton wool removed an entire layer. But the work's condition does little to lessen its astonishing beauty. Stare at the ethereal, lucent windows beyond the narrative action and you'll wonder if da Vinci's uncharacteristic short-sightedness wasn't divinely inspired.

English-language guided tours (€3.50 on top of the regular ticket price) take place at 9.30am and 3.30pm from Tuesday to Sunday – again, you’ll need to book ahead.