Mårten Trotzigs gränd is Stockholm's narrowest alley, a stepped passage in Gamla Stan that squeezes between old merchant houses. It is named for a German-born trader who became one of the city's wealthier residents in the late 16th and early 17th centuries.
The alley is a small stop, but a memorable one if you are already exploring the old town on foot. It gives a quick physical sense of medieval Stockholm's tight street pattern.