A long trip that was!
Altogether, a whole week on a train that goes from Moscow to Beijing (through Ulaanbaatar, Mongolia). Along the way, the train has to change a lot to adapt to different railway gauges (and you can stay inside the train or step out, either way you can witness the work involved).
When you stay 24/7 in a train, the train rhythms start to feel like the norm. Sleep and wake up happen whenever they feel like it, and every time you look outside the world changes significantly. I liked this journey more than I imagined I would.