It has been a custom with princes, in order to hold their states more securely, to build fortresses that may serve as a bridle and bit to those who might design to work against them, and as a place of refuge from a first attack.

I praise this system because it has been made use of formerly.

Notwithstanding that, Messer Nicolo Vitelli in our times has been seen to demolish two fortresses in Citta di Castello so that he might keep that state; Guido Ubaldo, Duke of Urbino, on returning to his dominion, whence he had been driven by Cesare Borgia, razed to the foundations all the fortresses in that province, and considered that without them it would be more difficult to lose it; the Bentivogli returning to Bologna came to a similar decision.

Fortresses, therefore, are useful or not according to circumstances; if they do you good in one way they injure you in another.

And this question can be reasoned thus: the prince who has more to fear from the people than from foreigners ought to build fortresses, but he who has more to fear from foreigners than from the people ought to leave them alone.