Out in the open water of the IJmeer, a few kilometres off the old fortified town of Muiden, a low circular fortress sits on an artificial island. This is Pampus, one of more than forty forts that make up the Defence Line of Amsterdam, a ring of fortifications built around the city in the late nineteenth and early twentieth centuries. The idea was simple and very Dutch: in case of attack, large areas of land around the city would be flooded to a depth that was too shallow for boats and too deep for soldiers to wade, and the forts would guard the roads, railways and dykes that crossed the flooded zone. Pampus guarded the approach to Amsterdam by water. The line was listed by UNESCO in 1996.
The fortress was never tested in battle, and by the time it was finished, advances in artillery and aviation had already made it obsolete. Today it is a museum, reached by ferry from Muiden, with exhibitions, tours and a restaurant, and the walk around the island gives fine views over the water and the skyline of Amsterdam in the distance.
Muiden itself is a charming little town, with a busy harbour full of sailing boats, and the Muiderslot, a moated castle from the thirteenth century, one of the best-preserved in the Netherlands. In the seventeenth century it was the home of the poet and historian P.C. Hooft, who gathered a circle of writers, artists and scholars there, known as the Muiderkring.
For riding, the area offers a mix of busy motorways and quiet dyke roads. The roads along the IJmeer and the Vecht river are pleasant, with views over the water and the meadows, and the Vecht, lined with grand country houses built by wealthy Amsterdam merchants, is especially beautiful. Weesp, a fortified town with canals and windmills, is a few kilometres away, and the area around Naarden, with its star-shaped fortress, is another fine destination. Muiden has fuel, shops and restaurants, and the ferry to Pampus runs on a seasonal timetable worth checking in advance. The weather can be windy on the water, and crossings may be cancelled in rough conditions.