Forget mountains and passes: the Dutch defended Amsterdam with water. Between the 1880s and the 1920s, the army built a ring of forts around the capital at a distance of roughly fifteen to twenty kilometres, the Stelling van Amsterdam, designed to flood the surrounding polders to a depth too shallow for boats but too deep to wade through. Forty-odd forts, along with dykes, sluices and batteries, formed the ring, and the area north of the city near De Rijp and the Beemster was part of it. The Defence Line of Amsterdam gained World Heritage status in 1996, and in 2021 it was extended to include the older New Dutch Waterline further south, the whole now known as the Dutch Water Defence Lines.
The forts are low, grassy mounds with concrete walls, often surrounded by moats, and they blend into the landscape so well that you can ride past one without noticing. They were built just as military technology was changing fast, and by the time the system was completed, aircraft had made it largely obsolete. It was never tested in battle. Today many forts have been converted into museums, restaurants, art spaces and nature reserves, and the moats are home to waterfowl.
The landscape around De Rijp is classic North Holland: flat polders crossed by straight canals and dykes, black-and-white cattle, windmills and wide skies full of clouds. De Rijp itself is a charming little town with wooden houses and a past built on whaling and herring fishing. The Beemster polder, drained in the early seventeenth century, is a UNESCO site in its own right, with its geometric grid of roads and ditches. Riding here means straight roads, tight bends on dykes, narrow lanes, and the constant presence of cyclists, who have priority and know it. Wind is the main challenge, and it can blow hard across the open polders.
De Rijp has a few cafés and shops, and larger towns such as Uitgeest, Purmerend or Alkmaar offer fuel and every other service. Local specialities include Beemster cheese, herring and apple pie. Take a short walk around one of the forts to see how the moats and earthworks fit together, then ride the dykes back toward De Rijp for a coffee by the water. It is gentle, open country, and on a sunny day with a light breeze, it is a joy.