In AD 47, a Roman general on a quiet frontier had a problem, which was how to keep his legions from getting restless. Gnaeus Domitius Corbulo, newly appointed to command in Lower Germany, solved it, according to the historian Tacitus, by making his troops dig. The result was a canal, the Fossa Corbulonis, linking the mouth of the Rhine with the Maas, so that ships could pass between the two rivers on a sheltered inland route rather than risk the open North Sea. It is one of the earliest known large engineering works of its kind in the Netherlands.
The canal's line is thought to run through the area of the Knippolder, between Leidschendam, Voorburg and Voorschoten, in what is now a quiet landscape of polders, ditches and suburbs. The Vliet, an old waterway that still connects Leiden and Delft, follows the same course in part, and the idea is that Corbulo's soldiers dug a channel along the line of an existing creek. Close by, in Voorburg, stood Forum Hadriani, a Roman town named after the emperor Hadrian. The canal is part of the Lower German Limes, which was inscribed by UNESCO in 2021.
What you get is a very Dutch ride along a line of water. The roads are narrow, often one-way for cars, with dedicated cycle lanes and speed bumps in the villages, and an occasional lift bridge that holds you up while a barge passes. Everything is well kept, with tidy gardens, little harbours and windmills. In spring the bulb fields to the north colour the horizon, and in winter, mist hangs over the polders in the early morning.
Voorschoten, a town of more than twenty thousand, has fuel and cafes, and larger towns like Leiden and The Hague are close. The Hague has its own interest, with the seat of government, a fine art museum with Vermeer's Girl with a Pearl Earring, and a beach at Scheveningen, so a ride here can take in a lot in a single day.
Sit by the water for ten minutes and think of the legionaries with their shovels.