See one climber's dizzying ascent of a mountain that was once considered impossible to master

National Park Week, a celebration of the 100-year anniversary of the creation of the National Park Service, began on April 16 and ends on April 24. For this week, admission is free at all national parks across the country.

Yosemite was one of the first to become a national park, more than 100 years ago on October 1, 1890 (before the National Park Service existed). It's home to one of the most notoriously difficult routes for both free and rock climbing: The Nose at El Capitan.

There are two main faces of El Capitan - the Southwest and the Southeast. The Nose lies between the two and is the most popular climb of El Cap. The 3,000-foot mountain was once considered impossible to climb due to the technicalities involved.

The very first successful rock-climbing ascent of The Nose wasn't until 1958, and until 1993, no one had successfully free climbed it. Since then, only four people have successfully completed a free-climb ascent of The Nose.

Free climbing - rock climbing using only your hands, feet, and ropes - can be very dangerous, but it can also be extremely rewarding. It can be done solo, with or without the help of safety gear to protect from falls, but not to assist on the ascent.

We got a chance to speak with one of those climbers, Jorg Verhoeven, and his photographer, Jon Glassberg, about their journey up The Nose.