Tommy Caldwell and new partner Jonathan Siegrist will head up El Capitan in Yosemite National Park tomorrow to return to Caldwell's longtime Dawn Wall project. With about 30 pitches, including seven of 5.14 and seven of 5.13, the Dawn Wall would likely be the world's hardest big-wall route when complete. Caldwell began working on the project in 2007, teaming up with Kevin Jorgeson in 2009. The climb will be the first on El Cap for Siegrist, who recently made the first ascent of Idaho's hardest route, the 5.14d Algorithm. Jorgeson, who is now on a rafting trip down the Colorado, will join the pair later this month.