At the heart of the Mongol Empire stood a marvel built by a captured Parisian goldsmith, Guillaume Boucher: a great silver tree whose serpent branches poured four drinks, wine, fermented mare's milk, rice wine and honey mead, when a silver angel on top blew a trumpet. A Flemish friar, William of Rubruck, travelled across Asia and saw it with his own eyes. In this hall Möngke Khan held a debate between Christians, Muslims and Buddhists. The words are imagined.