Boundary posts
In around 1875, the Ministry of War erected some 350 boundary posts along the length of the Kromme Rijn. The blue stone posts, marked with the letter O (for Oorlog, the Dutch word for war) and a number, marked the new route for transporting water to the New Dutch Waterline. The posts used to line up with plot boundaries. Many have been removed over the years, but the water board has returned 18 of them to their original location along the towpath between Werkhoven and Odijk following the construction of an environmentally friendly riverbank.