A sign at the City Hall in Münster
noting that the bar shown is one "Prussian Half Rod" long
A rod, a perch or a pole is a unit of length in the imperial and US systems.
In mediæval times English ploughmen used a wooden stick with a pointed tip to spur or guide their oxen. The rod was the length of this stick. In use from the 6th century, its modern value was standardized in the 12th century with Composito Ulnarum et Perticarum.
The rod is still in use as a unit of measure in certain specialised fields. In recreational canoeing, overland paths where canoes must be carried are measured in rods. This is probably because the length of a typical canoe is about one rod. In the United Kingdom, some gardens are measured in rods.