An implementation of the famous Berlin clock.  Misnamed the Mengenlehreuhr, or "set theory clock", it uses a series of blocks to represent the time in 24h format. The circle at the top blinks with the seconds.  The top row of blocks represents 5 hours each, the second row 1 hour each, the third row 5 minutes each, and the fourth row 1 minute each.  The time in the screenshot is 16:27.