Set Theory Clock
Berlin's Mengenlehrer Uhr or Set Theory Clock was commissioned by the Berlin Senate in 1975 and designed by Dieter Binninger and was originally located at Kurfürstendamm on the corner with Uhlandstraße. It was the first clock, which told the time using illuminated, coloured fields and was even included in the Guinness Book of Records. After it was decommissioned by the Senate in 1995, it was given a new home in Budapester Straße in front of the Europa Center through an initiative brought about by various business people in 1996.
The clock tells the time using the Mengenlehre or Set Theory Principle. The first row contains for red fields. Each of these fields represents five full hours. The second row is also made up of four red fields. Each of these fields represents a single hour. In this way, the clock can display a full 24 hour day.
Each yellow and red field in the third row represents five minutes. The red fields in the third row also mark off the completed quarter-hours, in other words 15, 30 and 45 minutes past. In the fourth row, each yellow field represents a single minute. Because the third row consists of eleven fields and the fourth row consists of four fields, a total of 59 minutes be displayed. 60 minutes are however not necessary, because this is represented as a completed hour.
The current time can be read by counting all of the relevant points mentioned above.