http://www.cnn.com/2003/TRAVEL/09/01/experimental.tourism.reut/index.htmlIn the same spirit as Georges Perec wrote a novel without ever using the letter "e," the hardy experimental traveller might walk in a straight line from a city's first street in alphabetical order to the last, a concept known as alphatourism.
In London, that makes for a 19-km (12-mile) trek from Abbess Close south of the Thames to Zoffany Street in the north. Alternatively, you could restrict yourself to destinations with double names, like Bora Bora or Walla Walla.