It spread Anglo-European culture across the nation and caused trade to flourish, but the story of the Chinese labourers who built the track has largely been forgotten.
Did Vikings find their way to a remote part of Oklahoma? Some in a small community believe so, thanks to controversial runic carvings found in the area.
In the 1800s, Livorno boasted Italy's top seaside resorts and most famous guests. These days, it's largely ignored – and tourists are missing out on a vibrant city full of surprises.
A drive down Bolivia's infamous "Death Road" takes travellers into a world where two resources have provoked fascination, misunderstanding and controversy for centuries: coca and gold.