“Paris Haute Couture,” from the Musée Galliera, offers a handpicked bouquet of history’s most stunning fashion. Not only can it be yours—it’s absolutely free. That’s because, like every exhibition at the Hôtel de Ville, the landmark tribute to Paris fashion is open to anyone. Its 100 dresses were chosen from more than 20,000, and the whole show is being sponsored by Swarovski. The Austrian crystals have lent their luster to haute couture since 1895.