What looks like an ordinary canal house turns out to have an entire Catholic church stashed inside. Ons' Lieve Heer op Solder (Our Dear Lord in the Attic) was built in the mid-1600s in defiance of the Calvinists. Inside you'll see labyrinthine staircases, rich artworks, period decor and the soaring, two-storey church itself. The museum completed a multi-year restoration project in late 2015, so the interior now sparkles.
