Centennial Fountain shoots a massive arc of water across the Chicago River. It spurts for five minutes straight every hour on the hour, from 10am to midnight from May through September.
The exercise is meant to commemorate the labor-intensive reversal of the Chicago River in 1900, which tidily began sending all of the city’s waste downriver rather than into the lake. (Chicago’s neighbors downstate, as you can imagine, do not go out of their way to celebrate this feat of civil engineering.)