The Duomo's fallen ball

Look up: at the very top of Brunelleschi's dome, above the marble lantern, a golden ball topped by a cross gleams in the sun. Now look down at the ground. Somewhere in the pavement, near Via dell'Oriuolo, a marble disc recalls the day that ball fell from the sky.

1Verrocchio's ball

The original sphere of gilded copper was made by Andrea del Verrocchio's workshop and hoisted into place in May 1471. A young Leonardo da Vinci was training in that workshop at the time, and years later he recalled in his notebooks how its pieces had been soldered. It measures more than two metres across.

2The lightning of 1601

Being the highest point in the city came at a price: lightning. The ball was struck many times, but the worst blow came in January 1601, during a night-time storm. The sphere broke loose and ended up in the square, while chunks of marble from the lantern rained down on roofs and nearby streets. Nobody was killed. Sources disagree on the exact day: some say the 17th, others the 27th of January.

The new ball was back in place in 1602, and according to the Opera del Duomo relics were placed inside it as a 'heavenly shield' against lightning.

Real protection only came much later, with the lightning rod installed in the 19th century.

3What to look for

• The marble disc in the pavement, near Via dell'Oriuolo.
• The golden ball above the lantern: picture the height of the fall.
• The cathedral's apses, in white, green and pink marble.