Route: Aconcagua (Argentina)

Aconcagua (22,841' / 6961m) is the highest peak in the Southern and Western Hemispheres, and in fact the highest peak on Earth that is not in the Himalayas. As such, and since the standard route ("Normal Route") is non-technical, it is a very popular climb.  From the highway at Los Penitentes (2580m), the route follows the huge and very gradual Horcones Valley for about 16 miles to Base Camp at Plaza del Mulas (4260m), and then proceeds steeply up to the summit through several higher camps.  FKTs have been reported for Plaza del Mulas to the summit, and from the highway to the summit.

Some earlier FKTs are mentioned in this article:  https://www.carreraspormontana.com/retos/martin-zhor-deja-el-fkt-de-ascenso-al-aconcagua-en-3h38/

For another interesting challenge, Sunny Stroeer circumnavigated and summitted Aconcagua in a single, 47h30m push ending on 2/3/2018.  This massive undertaking had previously been accomplished by Willie Benegas in about 32h.