Years ago, Michigan Avenue was merely Pine Street. Before that, it was a beach and the waters of the Lake Michigan would lap against the shore right about where Water Tower Place is now.
Back then Holy Name Cathedral (735 North State Street) was just a chapel in Our Lady of the Lake [Michigan] University. The college has since moved out to the 'burbs.
A lot has changed along the Lake Michigan shoreline, but there are still hints if you know where to look.
In Lincoln Park there is a long berm that looks like it serves no purpose other than to keep the snow from blowing in from the lake. But it's actually an ancient sand dune that helps mark the edge of what was once the Lake Michigan shoreline.
If you're intrepid enough, you'll find a marker in Lincoln Park showing you exactly where the water used to be. It reads,
"Abandoned Shoreline of Lake Michigan
This ridge is an ancient beach of sand bar of Lake Michigan whose waters reached this point 8,000 years ago when the lake level was 20 feet higher than now. Clark Street runs north top this ridge. The park ponds lie between such old beaches, abandoned by the shrinking lake.
The outer boundary of Diversey Harbor and the boat slip running south of it to North Avenue are man-made land.
The Chicago Park District"