A much abused subjective measurement of length (or time) employed mainly by the tourism industry to lie about their resorts.
eg "...hotel within walking distance of the beach..." should read "...hotel is miles away but with some sturdy shoes and some olympic thigh muscles you could walk it on a good day".
Also described by a lecturer at my university as, "less than five miles and not passing through any dodgy areas". A tall order indeed for most big cities.