The Oude Rijn (Old Rhine) is a branch of the Rhine delta in the Dutch provinces of Utrecht and South Holland. Its present-day length is 52 kilometres. In Roman times, it was the main Rhine branch, forming the northern border of the Roman Empire. In medieval times, it was used for river transport and there is a towpath along large sections of the river, many parts of which have been upgraded to roads over time. The river silted up in the course of the Middle Ages and had lost all of its importance by the 17th century.