The Dutch had a clever idea for defending their heartland: instead of building walls, they would drown the approaches. The Dutch Water Defence Lines, a World Heritage site, consist of a long belt of land around Amsterdam and Utrecht that could be flooded deliberately in wartime, with water deep enough to stop soldiers on foot and wagons, but too shallow for boats. Forts, dikes, sluices and pumping stations controlled the water. The New Dutch Waterline, built in the nineteenth and early twentieth centuries, ran south-east of Amsterdam through the area around Maarssen and the Loosdrecht lakes, and it was mobilised during the First and Second World Wars, though aircraft and modern artillery had made it largely obsolete by then.
Today the forts are hidden among trees, surrounded by moats, many of them restored and used as cafés, museums or event spaces. The fields that were meant to be flooded are green meadows, crossed by drainage ditches, with cows, willows and herons. Just east of here, the Loosdrecht lakes were created by peat digging centuries ago and now form a maze of water, reed beds and islands, popular with sailors and canoeists in summer.
The River Vecht, which flows north from Utrecht through Maarssen to Amsterdam, is one of the most charming rides in the country. In the seventeenth and eighteenth centuries, rich Amsterdam merchants built country houses along its banks, and the narrow road along the river passes manor houses, gardens, teahouses at the water's edge and old villages like Breukelen, which gave its name to Brooklyn in New York. The road is narrow and winding by Dutch standards and shared with many cyclists, so a calm pace is not only polite but necessary. The country is flat, but the wind can be strong, and rain showers come and go quickly.
Maarssen has fuel, shops and restaurants, as does Utrecht, a short way to the south. There are cafés at several of the old forts and along the Vecht, often with terraces by the water, perfect for a break. Try a portion of bitterballen, small crispy meat croquettes, or poffertjes, little pancakes with butter and powdered sugar, and if the weather is good, sit outside and watch the boats go by.