To the south of the city on the Naviglio Pavese, the Conca Fallata, or the Faulty Lock, shows the increased difficulty of surmounting a level change greater than 10 feet.

The engineer who successfully built this lock within a century of Leonardo, took on a more ambitious project proposed by Leonardo on the Adda river. He died in prison after several usuccessful, costly attempts. See Tre Corni Illustration.