Mount McKinley (20320ft, 6200m) is the top of North America. Because of its situation in Alaska, it is one of the coldest mountains on the earth. It is also bigger than its elevation suggests, since it raises quite abruptly above the plain, and due to the combination of altitude and weather, the ascension takes usually between two and three weeks. From mid-May to early June 1993, I climbed this mountain, partly by the West Rib (a technical route) solo.
Information on climbing McKinley on the Cold Mountain page