Premise: 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 Mus??e des Beaux-Arts.

Hypothesis: The facades of the Palais des Ducs had long since crumbled away into dust and no longer concealed the underlying structures.
Relation: contradiction