This is a massive loop which uses part of but not all of 3 different Rail Trail systems. These were at one point all railways. The 3 trail systems are the Ottawa Valley Recreation Trail, the K & P Trail, and the Cataraqui Trail.
https://www.ottawavalleytrail.com/
https://www.frontenaccounty.ca/en/things-to-do/kp-trail.aspx
This route is a combination of 2 established FKT routes in the small rural mountains of southwestern New Hampshire, combined for 123 miles and 25300 feet of vertical climbing feet. The first route is the SRKG or Sunapee Ragged Kearsarge Greenway, a 75 mile loop that summits the three aforementioned mountains and hosts annual 75 mile 3 day race https://www.srkg.org. The route for the FKT starts and finishes atop Mount Sunapee in Newbury, NH.
Bonelli trail is a 10-mile trail encircling Puddingstone reservoir counterclockwise at the Frank G. Bonelli Regional Park. This route begins at the San Dimas Ave. / Antonovich trailhead in San Dimas, Ca.
Ho Chi Minh City Vietnam to Phnom Penh Cambodia, a route I came up with as I wanted to find a way to connect 2 countries I have always wanted to visit. Well, it sure was an adventure alright. I figured I would start at a coffee shop in HCM, Coffee Goc Pho (the 83/50 location as it is a chain) and end at the Royal Palace in Phnom Penh, where the king of Cambodia resides. The route I mapped out is 144.7 miles, or 233 km. I wanted to take my time to enjoy the adventure, interact with the locals, and document what I learned along the way.