By overnight train from Belgrade (Serbia) via Skopje (Macedonia) to Thessaloniki (Greece). A video documentation.

More information and schedules:
Belgrade - Thessaloniki
Thessaloniki - Belgrade

Read more about this route in the new blog post written by Flo.

https://vimeo.com/121941458

And in the same compartment with us was Judith and Markus on their trip around the world. Have a look at their blog Where is Toad.