Sangallo was also a noted military architect, working on the fortifications of numerous cities such as Parma, Piacenza, Ancona and Orvieto. In Orvieto, he was also tasked by Pope Clement VII with building a well, called Saint Patrick's Well, noted as a marvel of engineering. Its double helix ramps around a central open shaft allowed oxen carrying water to go down via one of the ramps and up via the other without having to turn around; despite its 175-foot depth, the ramps are well lit through windows cut into the center section. Possibly an inspiration for the design was the Well of Joseph in the Cairo Citadel, also featuring a double spiral staircase.