This immense concrete block, rumoured to be anything from an ice house to a prohibition days casino, is actually the ruins of a dock built in 1919 by one Harvey Whitney. He had speculated - wrongly - that the city was about to rebuild an outer breakwater that would offer protection in this location. Without it, it proved almost impossible to safely unload from barges bouncing around on the lake and the dock was abandoned just three years after completion.
If you go:
The dock, also known as The Cribs, is one of many landmarks along Duluth's scenic Lakewalk, a walking, running, biking and rollerblading path that extends for three miles around Lake Superior.
Links:

The Lakewalk
(adjacent to the Hampton Inn)
Duluth Minnesota 55802 USA
cvb@visitduluth.com
Mailing address:
Canal Park
10 E Superior St Suite 200
Duluth, MN 55802 USA
Phone Numbers:
Visit Duluth
+1 (800) 438-5884
+1 (800) 438-5884