Anyone who spots an unusual, green, five-sided tower at Potsdamer Platz is looking at a piece of technological history: the traffic tower. Germany’s first traffic light!

In the 1920s, Potsdamer Platz was the busiest square in Europe. 20,000 cars, 26 tram lines and five bus routes jostled for space here every day. On 15 December 1924, the over eight-metre-high, five-sided tower officially came into operation — designed by the Berlin architect Jean Krämer, it was controlled from inside by a police officer using a stopwatch.

The tower quickly became a landmark of modern Berlin and even supplanted the Brandenburg Gate on postcards. In 1937, the original had to make way for the construction of the S-Bahn station. Since 2000, a faithful replica — donated by Siemens and Daimler-Benz — has stood once again on the site.

Photo Credit: Sean Zielinski via unsplash