Text: The elegant 17th- and 18th-century facades of the Palais des Ducs conceal the underlying Renaissance structures of the dukes' heyday, but many of their treasures remain to be seen inside, in the Musee des Beaux-Arts.
Entailment: The Palais des Ducs is an elegant 17th to 18th-century facade.
Contradiction: The Renaissance structures are not from the dukes' hayday.