Timeless classic? Berlin's Set Theory Clock
Although Berlin boasts more than its fair share of iconic timepieces, none is quite as quirky as the so-called 'Set Theory Clock' (Mengenlehreuhr), which stands on Budapester Straße beside the Europa Centre.
Easily mistaken for a sculptural installation, this bonkers but fabulous piece of '70s design certainly seems to make more sense initially as an art piece than timepiece.
Created by Berlin inventor Dieter Binninger and commissioned by the Berlin Senate in 1975, the clock uses a system of coloured lights to mark out hours and minutes.
Originally located on Kurfürstendamm, problems such as continually failing light bulbs (and, we suspect, the complete inability of most Berliners to fully fathom its time-keeping system) led to its decommission and threatened demise.
Fortunately for posterity, it's still with us today, and we've included a separate, handy guide for anyone wishing to attempt to unravel its mysteries.
Easy(ish) when you know how.
Berlin Set Theory Clock: Budapester Straße 10787 Berlin (next to Europa Centre)