Mengenlehreuhr, Public clock at Budapester Straße, Germany

The Mengenlehreuhr is a public clock on Budapester Straße that displays time through five rows of colored lights arranged on its rectangular frame. Each row serves a different function: red lights for hours, a mix of yellow and red for five-minute increments, and yellow lights for single minutes.

Commissioned by the Berlin Senate and designed by Dieter Binninger, the clock was installed on 17 June 1975 on the median of Kurfürstendamm at the corner of Uhlandstraße in West Berlin, and entered the Guinness Book of Records as the first public clock telling time with illuminated coloured fields. Its many incandescent bulbs made it costly to maintain, and after Binninger's death in 1991 the Senate decommissioned it in 1995. A business initiative had it re-erected in 1996 in front of the Europa-Center on Budapester Straße, where it stands today.

The clock displays time through colored lights and is often seen as a symbol of Berlin's connection to innovation and precision. Visitors stop to watch the play of lights and experience a completely different way of reading hours and minutes.

The clock is located near Zoologischer Garten station and is easy to find, as it sits on a busy street with clear signage. It helps to spend a couple of minutes watching the lights, especially as dusk falls, when the colors become more visible.

The clock appears in the unsolved K4 section of Kryptos, the sculpture at CIA headquarters in Langley, Virginia. Sculptor Jim Sanborn told The New York Times in 2010 and 2014 that positions 64–74 read "BERLIN CLOCK", and when asked whether this meant the Mengenlehreuhr he replied, "You'd better delve into that particular clock."