The Cat Cabinet
The Cat Cabinet (Het KattenKabinet) is puuurrfectly located in the 'Golden Bend' of the Herengracht. Situated on the classically-furnished piano nobile of a storied 17th-century canal house, there are many rooms full of cat paraphernalia (and real cats).
This house (and the one next to it) were once the property of the Van Eeghen family. In 1985 it was bought by the Stichting Herengracht 497 and restored, eventually becoming the feline-filled fantasy it is today.
It's an easy tram or bike ride from most places in Amsterdam.