From the outside, it is a typical seventeenth-century Dutch house beside a canal in central Amsterdam: but inside, Ons’ Lieve Heer op Solder is a hidden jewel not only in this vibrant, cosmopolitan city, but also the universal Catholic Church. The museum’s name translates to “Our Lord in the Attic”: because this ordinary-looking house contains an amazing surprise – a secret, but magnificent, Catholic church where, across 200 years, people worshipped and kept their faith alive.