The Royal Palace in Stockholm started with a defense tower. Probably it was there as early as the 12th century. Those who built it, and those who continued to build it during the centuries, understood the importance of surveillance here where hostile navigators otherwise would find their way into Lake Mälaren.
Eventually, the expanded tower had grown into a castle and around this castle the town grew. To protect the town, a wall was built. And when the first settlement grew out of its walls, a wider wall was built.
The castle was named Tre Kronor - Three Crowns, and became home of the Swedish kings until 1697. Every king who lived here until then expanded and changed the castle after his own taste. When the fire started in Tre Kronor on May 7th 1697, only the northern building - which was being rebuilt at the time - did not get completely destroyed.
Photo Slottet Tre Kronor 1661 by Govert Camphuysen is licensed under public domain