Museum Ons' Lieve Heer op Solder

'Our Lord in the Attic' is exactly what it sounds like: a complete, three-storey-high Catholic church built into the upper floors and attic of a 17th-century canal house, constructed around 1663 during a period when the Dutch Reformed city government officially banned public Catholic worship. The compromise Amsterdam quietly tolerated — as it did with several minority faiths — was worship in disguise: as long as a church wasn't visible or identifiable from the street, the authorities generally looked the other way.

What's remarkable is how complete the result is. Behind an ordinary merchant's house facade on Oudezijds Voorburgwal, the museum preserves an actual functioning Baroque church with a proper altar, a working historic organ, galleries and pews, all squeezed into a converted attic space across what were originally three separate canal houses joined together. It remained in occasional use as a church until 1887 and has operated as a museum since 1888, making it one of the oldest museums in Amsterdam.