In 1298 he was ordered to erect a dwelling-place for the Commonwealth, to the end that the people might be protected in their fortress from the violence of the nobles.

The building of the palace and the levelling of the square around it were attended with circumstances that bring forcibly before our minds the stern conditions of republican life in mediaeval Italy.

A block of houses had to be bought from the family of Foraboschi; and their tower, called Torre della Vacca, was raised and turned into the belfry of the Priors.

There was not room enough, however, to construct the palace itself with right angles, unless it were extended into the open space where once had stood the houses of the Uberti, "traitors to Florence and Ghibellines." In destroying these, the burghers had decreed that thenceforth for ever the feet of men should pass where the hearths of the proscribed nobles once had blazed.

Arnolfo begged that he might trespass on this site; but the people refused permission.