The Amstelkring takes its name from the group of historians who succeeded in saving it from demolition in the late 1800s. Good job they did save it, too, for what remains is one of Amsterdam's most unique spots, and one of its best-kept secrets. The lower floors of the house have been wonderfully preserved since the late 17th century, and offer a look at what life might have been like back then.
The main attraction is upstairs, and goes by the name of Ons' Lieve Heer op Solder, or 'Our Sweet Lord in the Attic'. Built in 1663, this attic church was used by Catholics during the 17th century when they were banned from worshipping after the Alteration. It's been beautifully preserved, too, the altarpiece featuring a painting by 18th-century artist Jacob de Wit. The church is often used for services and a wide variety of other meetings. Don't miss it.