Sredna Gora in the context of "Iskar (river)"

Northern Thrace or North Thrace (Bulgarian: Северна Тракия, Severna Trakiya; Turkish: Kuzey Trakya; Greek: Βόρεια Θράκη), also called Bulgarian Thrace, constitutes the northern and largest part of the historical region of Thrace. It is located in Southern Bulgaria and includes the territory south of the Balkan Mountains and east of the Mesta River, bordering Western Thrace and East Thrace in the south, and the Black Sea in the east. It encompasses Sredna Gora, the Upper Thracian Plain, and 90% of the Rhodopes.

The climate ranges from subtropical to transitional continental and mountainous. The highest temperature recorded in Bulgaria occurred here: it was 45.2 °C (113.4 °F; 318.3 K) at Sadovo in 1916. The main rivers of the region are the Maritsa and its tributaries. Notable cities include Plovdiv, Burgas, Stara Zagora, Sliven, Haskovo, Yambol, Pazardzhik, Asenovgrad, Kardzhali, Dimitrovgrad, Kazanlak and Smolyan. Northern Thrace has an area of 42,073 km.

Plana (Bulgarian: Плана) is a mountain range in western Bulgaria with an altitude of 1,337 meters above sea level. It is part of the Srednogorie mountain system that from west to east includes the mountain ranges of Greben, Zavalska Planina, Viskyar, Lyulin, Vitosha, Plana and Sredna Gora. Plana Peak in Tangra Mountains on Livingston Island, Antarctica is named after it.

The Sub-Balkan Valleys (Bulgarian: Подбалкански котловини, romanized: Podbalkanski kotlovini) are row of 11 valleys running from the Bulgarian border with Serbia east to the Black Sea. They are separating the Balkan Mountains from a chain of other mountains known as Srednogorie which includes Vitosha and Sredna Gora. There is great abundance of mineral waters. They are divided into two parts: Western (higher) and Eastern (lower). The western valleys include: Burel Valley; Sofia Valley; Saranska Valley; Kamarska Valley. The eastern valleys are: Zlatitsa–Pirdop Valley; Karlovo Valley; Kazanlak Valley; Tvarditsa Valley; Sliven Valley; Karnobat Valley; Aytos Valley.

42°15′N 26°0′E / 42.250°N 26.000°E / 42.250; 26.000

The Upper Thracian Plain (Bulgarian: Горнотракийска низина, Gornotrakiyska nizina) constitutes the northern part of the historical region of Thrace. It is located in southern Bulgaria, between Sredna Gora mountains to the north and west, a secondary mountain chain parallel to the main Balkan Mountains; the Rhodopes, Sakar and Strandzha to the south; and the Black Sea to the east. A fertile agricultural region, the Upper Thracian Plain proper has an area of 16,032 square kilometres (6,190 sq mi) and an average elevation of 168 metres (551 ft). The plain is part of Northern Thrace. The climate is transitional continental. The highest temperature recorded in Bulgaria occurred here: it was 45.2 °C (113.4 °F) at Sadovo in 1916. The precipitation is 550 millimetres (22 in) a year. Important rivers are the Maritsa and its tributaries, Arda, Tundzha, Stryama, Topolnitsa, and Vacha. Important cities include Plovdiv, Burgas, Stara Zagora, Pazardzhik, Asenovgrad, Haskovo, Yambol and Sliven.

Kalofer (Bulgarian: Калофер pronounced:[kɐˈɫɔfɛr]) is a town in central Bulgaria, located on the banks of the Tundzha between the Balkan Mountains to the north and the Sredna Gora to the south. Kalofer is part of Plovdiv Province and the Karlovo municipality. It is best known as the birthplace of Bulgarian poet and revolutionary Hristo Botev.

The modern settlement of Kalofer emerged in the 16th century, managing to preserve its Bulgarian character in the Ottoman Empire and to develop as a centre of craftsmanship, primarily cord production. The Kalofer monastery has been in operation since 1640 and the convent since 1700. During the Bulgarian National Revival the town became a centre of revolutionary activity, being the birthplace of figures such as Hristo Botev, Exarch Joseph, Dimitar Panichkov, and Nikola Ivanov. Today, it is best known for the imposing Hristo Botev Monument (one of many in the country).

Viskyar (Bulgarian: Вискяр) is a mountain range in western Bulgaria with an altitude of 1,136 meters above sea level. It is part of the Srednogorie mountain system that from west to east includes the mountain ranges of Greben, Zavalska Planina, Viskyar, Lyulin, Vitosha, Plana and Sredna Gora. Viskyar Ridge on Greenwich Island in the South Shetland Islands, Antarctica is named after it.

Lyulin (Bulgarian: Люлин) is a mountain range in western Bulgaria with an altitude of 1,256 meters above sea level. It is part of the Srednogorie mountain system that from west to east includes the mountain ranges of Greben, Zavalska Planina, Viskyar, Lyulin, Vitosha, Plana and Sredna Gora. Lyulin Peak on Livingston Island in the South Shetland Islands, Antarctica is named after it.