Speed on steel wheels has fascinated engineers for nearly two centuries, and a string of stunning records in the last twenty-five years has pushed railway engineering towards new frontiers. Japan - pioneer of high-speed train technology - set the precedent with its legendary bullet trains in 1964; since then a dozen countries have joined the high-speed revolution. Today, China is setting the pace as it crafts a nationwide network of super-railways, and Morocco and Saudi Arabia are on the cusp of launching trains that travel at 300km/h. The USA lags far behind, outpaced by Asia and Western Europe, where Eurostar links London to the international high-speed network - although a new-generation railway to northern England is still missing. Here is the full story of high-speed trains, retold in a journey across countries and continents.