Chicago Lakefront Trail
The benchmark for a city waterfront run. The paved trail follows Lake Michigan for 18 miles, from Ardmore Avenue in the north to 71st Street in the south, and since 2018 it has been split into a separate bike trail and pedestrian trail along its whole length, so you are not dodging cyclists at every bend.
Downtown hotels sit a short walk from the shore, so there is no need to plan more than a turnaround point: north or south, the skyline stays beside you. Wind off the lake is the one thing to plan for. Start into it and let it push you home.
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