I was reading today's newspaper about a (fantasy?) plan to dig a 65 mile rail tunnel between Russia and the USA under the Bering Striaght. What caught my imagination was the train trip that was sketched out in the paper:-
Mexico City, El Passo, Vancouver, Fairbanks, Anadyr, Magadan, Irkutsk, Omsk, Moscow and London.
But this is only the short trip.
Surely you would start at Cape Town and travel all the way up through Africa, Egypt, Iran (maybe not

) and up to Moscow. Then east through Russia, "the Bering Tunnel", Canada, USA, Mexico and down through South America finishing at Buenos Aires, maybe.
That would be an trip and a half..........
Wonder if you could get an Interrail ticket?