Excerpts from Books and Wikipedia
"Across the Danube River lies Romania’s southern neighbor, Bulgaria. The rugged Balkan Mountains form Bulgaria’s physiographic backbone, separating the Danube and Maritsa basins. As Figure 4-27 shows, Bulgaria has five neighbors, several of which are in political turmoil. In 2007, Bulgaria also became an EU member, once required judicial and other social reforms were finalized. But today its 7.1 million citizens constitute one of the Union’s poorest countries, and development prospects are not encouraging. Bulgaria fronts the Black Sea and has a major port at Varna, but the main advantage it derives from its seaside location is the tourism its beaches generate. The capital, Sofia, lies near the opposite, western border with Serbia, and in its core-area hinterland modest foreign investment is slowly modernizing parts of the economic landscape." [Geography: Realms, Regions, and Concepts, 17th Edition, p. 189, 191]