Castello Sforzesco, Milan

Castello Sforzesco is Milan’s formidable 15th-century fortress, housing Michelangelo’s last sculpture, the Rondanini Pietà, and Leonardo da Vinci’s iconic ceiling frescoes in the Sala delle Asse. Spanning over 500 years of history, its art collection surpasses #4’s medieval frescoes in both Renaissance pedigree and scale, with masterpieces spanning three centuries. The castle’s 70,000-square-meter grounds enclose seven museums, including the Museo d’Arte Antica with 1,500 pieces. Its defensive walls stretch 1.2 kilometers, and the Torre del Filarete stands at 70 meters tall, a symbol of Sforza power that rivals #2’s Roman origins in political significance.