As far as I know, Yen Tu Mountain is the only spiritual mountain I've "climbed". I've been to the top of Yen Tu twice, although I did not walk all the way from the bottom (6000 meters). Walking from the bottom takes about six hours and I didn’t have the time (or energy) to make the trek. On both of my trips I was with Trish Thompson and the Joyfully Together Mobile Retreat so we took the cable car about two-thirds up the mountain. It is still a good walk over rough terrain from the end of the cable care. The walk down was much easier using carved rocks and constructed steps. It is common to encounter fog on the mountain and on my last trip visibility was extremely limited.
In Vietnam: Lotus in the Sea of Fire, Thich Nhat Hanh (Thay) talks about the life changing journey “The great King-monk Tran Thai Tong made to meet with the “Venerable Truc Lam, the great monk and imperial counselor.”