Construction Update
What’s Underneath Chicago’s Urban Parks? Disappointment, If You’re a Worm

It’s always fun to listen in to tourists at Millennium Park ooh-ing and aah-ing at the amazing job the City of Chicago has done preserving such a large slice of nature in the heart of the city. The vast majority of them don’t know that underneath the wild-looking flowerbeds, the stately lawns, and the carefully channeled rivulet is a vast parking garage, and a commuter train station.

But that’s OK. They came to Chicago for a bit of escapism, and Chicago is happy to trade American dollars for a little sleight-of-hand.

Cascade Park under construction in January, 2021 (Courtesy of Loop Spy Carol)
Cascade Park under construction in January, 2021 (Courtesy of Loop Spy Carol)

The reason we bring this up is because of geofoam. Loop Spy Carol recently sent us some photographs of what will soon become Cascade Park. You can see massive piles of geofoam all over the place. The white slabs will eventually be arranged and covered over to form the base of the gentle slopes leading from Upper North Harbor Drive down to Lake Michigan. Another underground secret that will be trod upon by thousands of unsuspecting tourists.

Geofoam looks like the styrofoam blocks that are used to keep electronics from flailing around in their boxes during shipping. Except that geofoam blocks are often the size of a twin mattress, and instead of snugly embracing a big-screen TV, they’re doomed to spend life alone underground.

Cascade Park was designed by Claude Cormier + AssociƩs, and is expected to open ahead of schedule this summer.

To get an idea of how a park planed on top of geofoam looks, just wander across the street. The people who put Maggie Daley Park together made extensive use of geofoam in its construction. But the people up top think they’re walking on earth.

Location: 199 North Harbor Drive, The Loop

Author: Editor

Editor founded the Chicago Architecture Blog in 2003, after a long career in journalism. He can be reached at

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