The hall with the hidden wall

More than fifty metres long and built for a people's council of five hundred men, the hall behind these walls is the largest in the city, though you'd never guess it from the street.

From out here the town hall looks mostly like a fortress, with rough stone running all the way up and a tower that sits oddly off-centre. That lopsided position comes from the builders reusing an existing tower base that belonged to an old family.

The reason to step inside is within. The Salone dei Cinquecento, the Hall of the Five Hundred, was built for the council from the days of Savonarola, the friar who briefly ran the city, and later remodelled by the Medici into a show of power filled with battle scenes by Giorgio Vasari. Beneath one of those frescoes a puzzle may still lie, because Leonardo da Vinci began a wall painting here of the Battle of Anghiari, experimented with a technique that made the paint run, and left the work unfinished.

When Vasari rebuilt the hall fifty years later, he painted on one of his banners the words he who seeks, finds, and ever since researchers have suspected he preserved Leonardo's wall behind a new partition.

You need a ticket for the halls, the courtyard by the entrance is free to enter, and in the summer months the museum stays open late.

We walk out of the courtyard and keep to the right, towards the open colonnade on the corner of the square.