Famous hiking trail north of Copenhagen:

https://tisvildevejen.dk/

This is a great option for those visiting Frozen Head State Park who want a longer FKT option than just the Fire Tower. This is a classic, historic loop that used to resemble the Barkley Marathons course in its early days. Unlike the Barkley, however, this route is entirely on trails within the park. There is a Strava segment for the loop, so to claim the FKT, you must best the previous men's/ women's time. Begin at the park visitor center, then take the Storybook Trail instead of the road, and run the loop in a clockwise direction.