The 23 hour train ride across Mongolia and into China was interesting for 3 reasons:
1. We were sharing a cabin with a man who was smuggling (or transporting) an entire bike disassembled into 10 different parts and tucked into various corners of our coupe.
2. It took us through the Gobi desert - a dramatic change from the lush valleys that we had seen for the better half of the morning.
3. The border control with China was painless but what had us fascinated was the gauge changing process. The train tracks in Mongolia and China differ, so the train was pulled into a shed, the train carriages were literally pulled apart like Lego pieces and lifted up while the gauges got switched. All of this while the passengers were still in the train!