Romantic knightly castles with round towers and pointy roofs stand against a background of tulip fields and wind mills. They have already become the pride of the Netherlands long time ago. Undoubtedly, their localisation nearby sea routes, valleys, and river mouths is a distinctive feature of these medieval Dutch strongholds. Such places not only provided good defence but also allowed to collect customs duties from trading vessels. Deep moats surrounding many Dutch strongholds were filled with water to the brim during floods. As a result, they turned castles into impregnable fortresses standing, as it seemed, on an island. A good example of «water castles» of this type includes Muiderslot, erected in the 13th century at the mouth of the Fecht River, and Heeswijk Castle whose strong walls change colour depending on the seasons. Over the 17th and 18th centuries, when not strong or massive walls were valued but subtle and sophisticated structures as well as park and garden art, many medieval Dutch castles were modernised in the Rococo and Classicist style, enrapturing with their beautiful gardens and parks even today.