Bulgaria is bordered on the North by Romania, on the East by the Black Sea, on the South by Turkey and Greece, and on the West by Yugoslavia and Macedonia. Bulgaria comprises portions of the classical regions of Thrace, Moesia, and Macedonia. The southwest of the country is mountainous with two alpine ranges - Rila and Pirin and further east are the lower but more extensive Rhodope Mountains. Rila mountain includes the highest peak of the Balkan Peninsula, peak Musala at 2,925 meters (9,596 ft); the long range of the Balkan mountains runs west-east through the middle of the country, north of the famous Rose Valley. Hilly country and plains are found in the southeast, along the Black Sea coast in the east, and along Bulgaria's main river, the Danube in the north. Other major rivers include the Struma and the Maritsa river in the south.

The Balkan peninsula derives its name from the Balkan or Stara Planina mountain range which runs through the centre of Bulgaria into eastern Serbia.

The largest cities in the country are Sofia (1,246,791), Plovdiv (376,918), Varna (345,522), Burgas (259,985), Rousse (177,538), Stara Zagora (163,193), Pleven (121,700), Dobrich (115,861), Sliven (100,300).

The Bulgarian climate is temperate, with cold, damp winters and hot, dry summers, and Mediterranean along the Black Sea coast.

Temperate continental with clearly marked four seasons. A Mediterranean influence is felt in the country's southern regions. The average annual temperature is 10.5°C. The average January temperature is around O°C. Average summer temperatures rarely exceed 28°C.