About a ten-minute bicycle ride from the city centre, you’ll find several large forests, one of them as part of Clingendael Landholding. Clingendael Landholding is holder of many things: ponds, playgrounds, a Japanese garden (great for wedding photos), a refurbished mansion (where colleagues at the Clingendael Institute, an international development-oriented NGO, meet to save the world), and my favourite thing about Den Haag, its military bunkers.

You’ll find them all over the Bos, but the deeper you explore, the more interesting they get. One bunker holds an experimental radio station (I will admit I have never tuned in). Several are so big that their tops are covered in trees and grass, creating mini-forests of their own; climbing up the bunkers by tree roots is an adventure in itself. But it’s the opportunity to explore the interior of the military bunkers that brings me the most joy. I’ll play hide-and-seek with my daughters, and before I know it they have discovered some secret room where, in the darkness, there might be some electrical wiring and a fuse box left over from World War II. On the way home, my girls will ask where all that hi-tech, sci-fi gear came from, and I’ll get to decide whether to tell them the truth, or simply weave this information into a fantasy story about monsters hiding under the mountains of “De Bos.”