I'm writing this from a hostel in Belgrade, having spent nearly all of the previous day getting here by train.
Along the way I got to see a glimpse of the space between the two cities. One can tell whether a village is Bosnian, Serbian, or mixed by whether it has a minaret, a church, or both. Otherwise the villages look very much alike.
Bosnia is mountainous and our train travelled slowly, winding round valleys and sometimes leaning over so far it felt like it might fall off the tracks. When we got into Serbia it turned flat and the train went much faster. At one point we were ordered off the train by a man in uniform. Nobody knew what was going on or where we were. Eventually it turned out we were just changing trains.
On the train I discovered that both groups of people adjacent to my cabin were also from west London. One group was from Slough and the other from Staines. It's strange how often one travels across the planet and ends up next to the same people.
Belgrade is very different from Sarajevo. It is big, loud, busy, filled with traffic, and dominated by communist era buildings. I have so far only had a chance to explore it at night, but I plan to see it properly today.
One of the most obvious differences between Serbia and Bosnia is that, although the Bosnians and Serbs both speak the same language (Serbo-Croat), the Serbs write it using the Cyrillic alphabet and the Bosnians write it using the more familiar roman alphabet. Cyrillic can be quite confusing. Most of the letters look familiar but few are pronounced the way to expect. It is like reading something written using a Caesar cypher.