Global Adviser

Amsterdam is renowned as Europe's favorite Sin City, but it does have its share of spiritual offerings to balance the wicked. And one of its best — yet least known — is tucked right in the heart of the red-light district.

If you find yourself here among the city's bars, hash cafés and dumbfoundingly brazen brothel shop windows and are seeking something to stimulate the soul instead of the body, head to the Amstelkring Museum on Oudezijds Voorburgwal. Its informal (yet more common) English name, the Church in the Attic, gives a more vivid sense of what it is: a resplendent 17th century Catholic church built into the vaulted and surprisingly airy top floor of one of Amsterdam's iconic canal houses.

If you have trouble finding it, that's by original design. This is the last of what were once hundreds of attic churches that Catholics quietly built into the top floors of homes so they could pray unmolested after public Catholic worship was banned in 1578. Being pushed underground (or, rather, upstairs), as this museum demonstrates, did not diminish the Catholics' zeal for the pageantry and ornamentation that ran contrary to the more austere religious praxis of the time. The 150-seat chapel is a marvel of high-church pomp packed into an amazingly compact space, with gilded monstrances, a full pipe organ and a side chapel dedicated to the Virgin Mary.

Don't miss the rest of the house, which was bought in 1661 by a wealthy Catholic merchant who began work on the church almost immediately. Its period rooms restored with original furniture and artwork show with understated efficiency what domestic life in Amsterdam was like between the 17th and 19th centuries. And don't worry about your friends back home finding out that you dropped by a church during your visit to this city of iniquity ("You went where?"). Just tell them what happens in Amsterdam stays in Amsterdam.