Our Lord in the Attic Museum (Former Hidden Catholic Church)

"This stunning Golden Age house has a hidden asset: during the persecutions of the Protestant Reformation, the merchant owner had an entire Catholic church constructed under the eaves. (You don’t need to be a believer to appreciate it, but if you are, they still hold Mass the first Sunday of every month except in July and August). Top billing goes to said attic space, now restored to its 1862 glory, and the audio tour, packed with strange and surprising facts about how the owners lived. Best of all, the foot traffic is about one-twentieth of what you'll encounter at the Rijksmuseum. We're sold." - Clodagh Kinsella, Jennifer Ceaser

"Amsterdam is known for its religious tolerance, but beginning in the 16th century, during the Protestant Reformation, Catholics were prohibited from holding Mass publicly. And so “hidden churches” began popping up in private homes around the city; the only remaining example is this one, tucked inside a 17th-century canal house in Amsterdam’s red-light district. Occupying the building's topmost levels—hence the name Our Lord in the Attic—this place of worship, which holds around 100 congregants, is surprisingly spacious, with a double-height ceiling created by cutting away a portion of the upper floor. The chapel’s lovely altar is flanked by religious statues and wood columns painted to resemble marble; a large oil painting, Baptism of Christ by Jacob de Wit, hangs over the pulpit. Catholic services are still performed here (in Dutch) on the first Sunday of every month, from October to May."