A 17th-century clandestine church hidden in a canal house’s attic, this museum reveals how Catholics worshipped in secret during the Protestant Dutch Republic. The three-story church, complete with altarpieces and pews, was built in 1663 and remained hidden for 200 years. The original kitchen and living quarters of the merchant family who owned the house are also preserved. A remarkable example of religious tolerance’s limits—and ingenuity.