In 1606, Christian IV bought a vast expanse of land outside the city walls that he turned into a garden, nowadays the Royal Garden, in which he built a "folly" that over the years was transformed into a castle. The most advanced techniques of the time were used here, including bathrooms with running water, and a drawbridge operated from the winter salon. In 1710, the palace ceased to be a royal residence as Frederik IV considered it too small. Since 1833, Rosenborg has housed the Crown Jewels.