Having survived long centuries, political upheaval, and even bombings during World War II, Leonardo Da Vinci’s masterpiece Last Supper now faces the risk of damage from air pollution due to its location in one of Western Europe’s most polluted cities. In late 2009, the refectory of Santa Maria Delle Grazie Church, where the painting is located, installed a sophisticated heating, ventilation, and air conditioning system to protect the painting from the polluted air of Milan.