Ferrara is another well-preserved historic city and a UNESCO World Heritage northwest from Ravenna. This one was ruled by the powerful Este family throughout the Middle Ages, who constructed all the beautiful palaces and cathedrals and other architectural gems. In the very heart of town is a massive Castello Estense – with turreted towers, high and thick walls and even a full moat around it – supposedly this castle was meant to protect the family against the rebelling local citizens and not foreign invaders. Another palace – Palazzo dei Diamanti, and a spectacular Cathedral di San Giorgio are just next door across the Piazza Ttrento, and still further are merchant houses of Loggia dei Merciai. Ferrara is easy to explore, with wide open streets and all attractions concentrated in its Centro Storico.