| According to what were the requirements of military architecture in the 15th to 17th centuries, the ramparts are configured as small but strong fortresses. The bastion Carlo V is triangular. Beside there's Porta Napoli that is the oldest gate of the city and was built by Emperor Frederick II Hohenstaufen, who with the aim of strengthening the defences of the city also built the Castello Svevo (Castle Swabian). |