Ons' Lieve Heer op Solder, otherwise known as ‘Our Dear Lord in the Attic', is a hidden gem situated in the centre of Amsterdam. Dating as far back as the mid-1600s, this seemingly ordinary canal house hides an entire Catholic church within its walls - built in defiance of the Calvinist beliefs prominent in the city at the time. Upon entering, visitors can explore the winding staircases, admire period decor and observe the remarkable artworks on the walls, before reaching the two-storey towering church itself.