The Parklands sector of the Louisville Loop is a purpose built bikeway that winds it's way thru 5 parks along Floyd's Fork river just east of Louisville.
This 19 mile one way/38 mile round trip bikeway features lots of curves, bridges, switchbacks and elevation changes which make it a unique topographic cycling experience.
There are plenty of YouTube videos which cover this bikeway. Everything from a leisure pace to a full-attack POV perspective.
As you will see in the linked video, the scenery along this bikeway ranges from rural to backcounty.
Sometime this season, I plan to ride it both ways the 1'st time at Recon Speed (15 mph) and then the following day both ways with my Foot in the Gas.
Attached are links to a map plus a video.
Retro out.