The London Underground's Tube Map is an icon of modern design. It has transcended its original purpose, becoming a brand unto itself. The map's original designer, Harry Beck, broke the most hallowed rule in the cartographic textbook when he created the map in 1933--that geographical accuracy is fundamental to a map.

While dispensing with geospatial accuracy and centuries of map-making tradition, Beck chose to permit only horizontal, vertical and 45 degree lines for his map. Beck also adopted classic British railroad typography and strong colour coding to render a simple visualisation of a highly complex network. Beck's original design has evolved over decades, surviving almost intact and passing the acid test for a "design with legs"--can it adapt and continue to function?

At Cleartrip, we're great admirers of Beck's design for an altogether different reason--the London Underground map is one of the best examples of interface design around. London is a vast and chaotic metropolis and Beck's design does a fantastic job of making it easy for "users" to navigate the city of London.

Beck's map combines with Transport for London's extensive design standards to create a consistent and easy user interface with all the characteristics of great interface design--simplicity, consistency and context.