___ Political Map of Bulgaria

Bulgaria is a quite mountainous country especially in the western and central areas, plains occupy only about one-third of the territory. Situated in southwest is the Rila mountain range where Bulgaria's highest mountains are located, with an elevation of 2,925 m the peak of Musala mountain is the highest point in Bulgaria and the Balkan Peninsula. East of Rila are the Rhodope Mountains, a karst landscape with deep river gorges and large caves.
North of the Rhodope are the Balkan Mountains, the range extends from Serbia south and parralell to the Danube River, with foothills near the Black Sea in east.
Between the Balkan Mountains and the Danube is a hilly, fertile lowland, known as the Danubian Plain. Another lowland is in the southeastern corner of the country, known as the Upper Thracian Plain, a fertile agricultural region, it is the northern part of the historical region of Thrace. Major rivers are the Danube, which defines most of the border with Romania, Maritsa (Evros), the longest river that runs solely in the interior of the Balkans, the Iskar, a tributary of the Danube.