Two rock climbers have completed what is considered the hardest climb ever: the vertical ascent of Yosemite National Park’s El Capitan, a rock formation in Yosemite Valley, without ropes.

The two climbers, Tommy Caldwell, 36, and Kevin Jorgeson, 30, were “free climbing”—or scaling a wall with your hands and feet, and only using ropes to catch your fall. What’s more, they climbed the Dawn Wall, the formation’s most difficult route, which had never before been climbed without the aid of ropes. Caldwell and Jorgeson reached the summit Wednesday.

Watch today’s Know Right Now to find out more about the hardest climb ever.