3Château de Chambord, France

There’s no better example of the transition from the fortified castles of the medieval era to palatial homes of the Renaissance than this enormous chateau in the Loire Valley. Commissioned as a “hunting lodge” by King François I in the early 16th century, the massive structure (440 rooms) took 28 years to construct.

However, the moat, corner towers and keep are purely decorative. Chambord is celebrating its 500th anniversary this year with myriad special events including an exhibition that addresses the question of whether Leonardo da Vinci designed the castle’s double helix staircase.