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.