2. Union Square’s Digital Clock

The rapidly ticking of numbers in Union Square is a mystery to many. Even lifelong New Yorkers might not know what they really mean, although some have suggested that they could represent the national debt number or the number of rainforest acres being destroyed. Both of these guesses, however, are incorrect — the numbers are actually a digital countdown of the hours within a given day.

The digital clock was installed over 15 years ago by Kristin Jones and Andrew Ginzel in partnership with the Public Art Fund for The Related Companies. The numbers count the 24 hours of the day, while also showing the remaining hours in the day.For example, in this photograph, the time is 8:21 (or 20:21 in military time), with an additional 26.5 seconds. Reading from the right side, there are 3 hours, 38 minutes, and 33.4 seconds left in the day. The center digit counts hundredths of a second. According to the Public Art Fund website, the digital clock is “meant to convey the energy, exhilaration and ultimate flux that is the essence of New York City.” Read more about the Union Square clock here.