This is a fascinating challenge and could technically be done anywhere with 3 individual 6000m mountains. This was first done (to my knowledge) by legendary climber Christian Stangl in 16 hours, 16 minutes. The idea was to reach the summit and descend from three different 6000m+ mountains. I proposed the following standardizing rules ahead of my 2022 attempt.
1. Route must go to the summit of 3 different peaks
2. Route must have at least 1000m of net gain per summit
3. Each mountain route may begin and end at the same or different location, but must have the same amount of ascent and descent (e.g. if you want to traverse a peak to save time, that's fair game, as long as the net up and net down are the same)
4. Runners can use car, bike, or travel entirely by foot
The clock starts when you start off on your first climb and stops when you return to the bottom of your 3rd climb. It does not stop for transit between peaks.
Again, technically this could be done on any 3x 6000m peaks in the world. I'm not sure there's a better place than the Puna de Atacama in Chile, but it's a very interesting logistical as well as physical challenge.