Nelkenweg is a 42km distance roundtrip in middle germany. Almost Trails and around 1000m vertical Gain. The route is pretty marked with sings showing an white N in a circle on black ground, styled as the typical hiking sings in germany.

https://www.teutoburgerwald.de/natur/in-der-natur/tour/nelkenweg-reizvo…

The Regional Trails in Minnesota are top notch! The Dakota Rail begins in picturesque Wayzata and takes you on journey through Lake Minnetonka’s many bays, towards Lake Waconia, and then out into the country! This is a paved, straight forward trail that has views for miles, literally. Perfect outing for people who like to run marathons on their own time…or ultrarunners looking for a relaxing training day!

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This iconic route follows the original London 1908 Olympic Marathon from Windsor Castle to White City in West London. Its distance (26mi 285yds, or 42.195km) would notably become the standard modern marathon distance (officialised in 1921).