The Bulgarian city of Ruse (also written ‘Rousse’) sits on the right bank of the Danube just opposite the Romanian city of Giurgiu, and is one of the country’s most attractive cities. Sometimes known as ‘Little Vienna’, thanks to the plethora of Neo-Baroque and Neo-Rococo architecture, it’s a highlight of any cruise along this stretch of the Danube.

The riverside town of Vidin is situated in the north west corner of Bulgaria, close to the border with Romania and Serbia. The architectural highlight is the magnificently well preserved Baba Vida fortress, and the town is also home to a mosque, a synagogue and several churches.

As the Danube wends its way east, along the border between Serbia and Romania, the river narrows to a dramatic gorge known as the Iron Gates. The river here is flanked by a huge stone carving of Decebalus, the last king of the Dacians and a Romanian national hero.

Belgrade has been invaded and occupied dozens of times over the centuries, a fact that's reflected in the mish-mash of architectural styles, from Ottoman and Art Nouveau to grim relics of the communist era. But Belgrade is also a city with real soul, emerging from a difficult recent history as one of Europe’s most exciting capitals.

Vukovar is one of the great tragedies of the Balkan wars, a once prosperous and elegant city reduced to rubble by fierce fighting between Croats and Serbs. There are green shoots of optimism as the city rebuilds, but the battle-scarred streets are a powerful reminder of the devastating conflicts of the 1990s.