It is the eighth of September, 1404. In a garden palace outside Samarkand, Ruy González de Clavijo, ambassador from the court of Castile, is brought before Timur, the lame conqueror who has made this Central Asian city the wonder of the age. Around them rise domes of glazed tile the colour of mountain lakes, and the air carries the sound of masons' chisels from construction sites that have not paused in thirty years.