I would simply be remiss in my blogly duties if I didn't link to Rachel Leow's amazing journey-via-Google-Maps through The Travels of Marco Polo.
As I commented over on that blog:
There have always been two great moments for me in Marco Polo’s travels.
1) The account of the Khan’s fiat paper currency, which he exchanges for all the gold and silver and jewels in his kingdom, and which everyone honors on pain of death;
2) The Khan’s network of recruiters and inspectors who likewise gather the most attractive maidens of every kingdom conquered by the Khan, who then keeps them as sexual and body servants before marrying them off to other nobles (usually his relatives). There’s a single Y chromosome signature that is overrepresented throughout most of Asia, suggesting a single common ancestor. Scientists believe that ancestor may be Genghis Khan.