The kastro stands on the site of the acropolis of ancient Patrai. The Romans were the first to build a fort here around AD 550, but the present structure is of Frankish origin, remodelled many times over the centuries by the Byzantines, Venetians and Turks. Set in an attractive pencil-pine park, it is reached by climbing the 190-plus steps at the southeastern end of Agio Nikolaou. Great views of Zakynthos and Kefallonia are the reward.