Fort Ronduit in Gooise Meren

You're standing at Fort Ronduit, just north of the fortified town of Naarden. Back in the day, the Zuiderzee lapped right up to here. Look at the wide moat around the fort. It's between twenty-five and thirty-five metres across, and the only way in is over a drawbridge. Behind the water rises a high earth rampart, with spots where the cannons stood.