The Pisco Sour, a Whiskey Sour variation, was invented by Victor Morris in Lima, Peru, in the early 1900s. He likely used lime juice, but most Pisco Sours today use lemon. Shaking the drink first without ice (a.k.a. dry-shaking) emulsifies the egg white and gives the drink an airy texture.
Slideshow:Great Classic Cocktails