Notre Dame Cathedral, Paris, begun 1163This view offers a fine example of the twin towers (left), the spire, the great rose window over the south portal (center), and the flying buttresses that support the walls and the vaults. Like hundreds of other churches in medieval Europe, it was dedicated to the Virgin Mary. With a spire rising more than 300 feet, Notre Dame was the tallest building in Europe at the time of its construction. (David R. Frazier/Photo Researchers, Inc.)