A huge underground art installation in Vienna will show you your reflection against a backdrop of real-time sociological statistics, like the number of days until Chernobyl will be safe for human habitation (hint: don't plan on moving there anytime soon). Weighty topics like the number of war casualties since Jan. 1 are balanced by fun facts, such as the number of Viennese in love today. The idea is to create a connection between passersby and the statistics being shown. Still, it would suck if you had to pass by it everyday on the way to work and you kept seeing the stat for how many people hate their jobs.
The thing is called Pi because… well, it's pretty complicated actually. There's like a 200-word explanation on the site you can read. But the gist is, because the number of digits in pi is infinite, it's the best way to symbolically represent the world. And yes, 478 of those digits are etched into the wall, in case you were wondering.