Wiki: https://en.m.wikipedia.org/wiki/Muiden_Castle

Streetview: https://goo.gl/maps/LksdqxGA9G1MvUA26

The original defensive castle was built for Count Floris V in about 1285. At the time, it was just thick walls (1½ meters thick in some places) and four short corner towers. Soldiers camped in the courtyard. It stands at the mouth of the Vecht River which was an important trade route at the time. Floris, though, was killed by his own nobility during a hunt about ten years later, and they destroyed his castle while they were at it.

Starting in 1370, the castle was rebuilt and expanded. About 200 years later it was further strengthened by adding additional fortress walls around it.