I just found out about this really unique spot in Colorado I will have to go to next time I'm there.
The Manitou Springs Incline, or locally known as "The Incline".
Photo via visitcos.com
Originally a cog railroad to haul equipment up to Pikes Peak. The rails were removed in 1990 and now since 2014 is open to the public as a trail/staircase. This trail raises over 2000 ft in under 1 mile so it looks like a challenging hike and appears to turn to stairs as you near the top.
This is going on the Life List.