Fort benoorden Spaarndam in Velsen

You're standing by Fort benoorden Spaarndam, the fort north of Spaarndam, on the Zijkanaal B. It's part of the Defence Line of Amsterdam, the ring of fortifications around the Dutch capital. Look at the water first. That wide, wet moat is hard to miss. And its outer bank gives away a secret: the fort ended up smaller than first planned, and the bank still follows the older, larger outline.