Lake Como is shaped like an upside-down Y, left by a glacier that carved three arms and left a lake over 400 meters deep. Rich Romans built villas here, and Pliny the Younger was born in Como itself. After the Romans came silk merchants, Milanese aristocrats and Napoleonic politicians, who built the neoclassical villas you can still walk through.
Three days is the right length, with one condition: you stay on the lake and you let the boats set the pace. The distances look short on the map, but the shore roads are slow and the best villas are on opposite sides of the water. Three days gives you Como, the west shore and the central triangle of Bellagio and Varenna. The honest catch is the calendar: from November many villas cut their days sharply or close.
Day one is Como town and the funicular to Brunate. Day two is the west shore: Villa del Balbianello, a section of the Greenway, and Villa Carlotta. Day three crosses the lake to Bellagio, Villa Melzi and Varenna. Start on a Friday: Balbianello is closed on Mondays and Wednesdays, Villa Monastero on Tuesdays (and Wednesdays from November), and the Duomo limits tourist visits on Sunday. A Friday start puts the villas on a Saturday and Sunday, when they are all open. Our Italy page covers the wider country. Most people arrive from Milan, and Lugano is a short train ride across the border.