The Nordertor is Flensburg's most recognisable building — a round-towered city gate from the late sixteenth century that stands at the northern end of the old town pedestrian zone. Built in brick with a distinctive pointed roof, it marks the historical boundary of the city and has been a symbolic landmark in the Danish-German border region for four centuries.
The gate now contains PHÄNOMENTA, a hands-on science centre aimed primarily at children and families, which makes it accessible at the cost of some dignity. The exterior is what most visitors come to photograph. The gate is visible from some distance along the pedestrian zone and serves as a natural turning point for a walk through the old town.