Ancient Bristlecone Forest climb, from day 2 of Everest Challenge.
Distance 21 miles
Avg Grade: ~6%
Tops out at over 10,000'
Final 3 miles average 10%
Don't remember how long it took, 3 hours maybe?

There were 2 other climbs comparable to this one during Everest, but this was after 180 miles of racing in elevation, and the one I'm most proud of.