Michael Finkel

Tighter, neater, faster -- Steven Allen may be the best wall builder in the world

Technical tree climbing, with its own vocabulary and specialized equipment, has won enthusiasts in the American West and elsewhere

Riding a unicycle up and down mountains requires the balance of a gymnast and the temperament of a teenager.

Each spring some eighty Army Rangers seek to demonstrate that they are the hardiest and most multi-talented athletes in the world.