The castle was built by Byzantine emperor Justinian I after the catastrophic earthquake of 551, re-using building material from pre-Christian structures. One of these spolia, the torso and head of a marble Roman statue, became part of the city's folklore, a sort of genius loci. It is known as the "Patrinella", a maiden who is supposed to have been transformed into a man during Ottoman times, guards the city against disease and weeps whenever a prominent citizen of Patras dies.