What is the longest escalator in the world?

Central-Mid-Levels escalator: in Hong Kong, tens of thousands of commuters travel each work day between Central, the central business district, and the Mid-levels, a residential district hundreds of feet uphill, using this long distance system of escalators and moving walkways. It is the world's longest outdoor escalator system (not a single escalator span), at a total length of 2,600 feet (790 m). It goes only one way at a time; the direction reverses depending on rush hour traffic direction. 

The longest individual escalators in the world are found in the "metro" or "subway" systems in several cities in Central and Eastern Europe
The tallest escalator on the London Underground system, and indeed in Western Europe, is at Angel station with a length of 197 feet (60 m), and a vertical rise of 90 feet (27 m). 

http://en.wikipedia.org/wiki/Escalator