Back in 2017, I took a train from Pune to Mumbai in India. The ticket said it was a superfast train, and we covered 150km in 4.5 hours. I never thought I'd experience that kind of speed in Europe too.

I took an overnight train from Belgrade to Podgorica. We covered 440km in 12 hours. Pretty much on par with that Indian train, except here at least they don't call it superfast.

No air conditioning on the train—the saving grace is the windows that actually open. It's an old train, the kind you see on Russian Railways. But for 30 euros, you'd expect something more comfortable (this is a sleeper cabin; there are also regular seats, which are cheaper). People warned me that the cars often smell like smoke, but I guess I got lucky. My neighbor wasn't smoking, and there was no tobacco smell at all.

It's a night train, but once we got to the Montenegrin side, it was already getting light. I couldn't tear myself away from the window. The tunnels kept blocking the view every now and then—sometimes for several minutes at a time.

The sheer number of tunnels and bridges, and the engineering effort that went into them, is impressive. Definitely worth taking this route at least once.