A sunken road is a path that has been cut into the surrounding terrain up to 10 metres deep by centuries of use by wagons and livestock as well as run-off rainwater. Wikipedia
Gorge between Gronau and Schönberg. According to tradition, when the vintage was particularly good, the people of Gronau avoided the delivery of the annual tithe wine to the Count of Schönberg by dropping a water-filled wine barrel into the gorge...