Nancy doesn't really belong to France's world-class sights and cities, but it has atmosphere, charm, and culture nonetheless. By a curious twist of history, a former king of Poland came to rule Lorraine in the first half of the 18th century and set about transforming the city into something more modern than he had inherited (something like Augustus changing Rome from a city of bricks into one of marble). The result can be seen today, and the squares, palaces, residences, and parks that constitute the historic core of Nancy form a Baroque ensemble that is very pleasant and well-preserved. Again, not an absolute must-see sight, but worth a detour if you are in eastern France.