Castello Sforzesco, Milan Duomo and Bone Chapel Walking Tour. Travel back in time to the Middle Ages on this 3-hour, small-group walking tour in Milan. You’ll admire views from the rooftop of the famous Duomo, the largest Gothic cathedral in Italy, and visit the beautiful Castello Sforzesco. The tour will also take you to San Bernardino alle Ossa's ‘Bone Chapel,’ an under-the-radar site full of character. Avoid the hassle of a big group with this small-group tour, designed for 15 people or less. Book and Save 20%: Castello Sforzesco, Milan Duomo and Bone Chapel Walking Tour.