Kyustendil
Set in the westernmost corner of Bulgaria, this province is centred around the shallow Kyustendil Valley, containing the region's major city and a famous balneological resort. The area is primarily Thracian in terms of culture and historical artifacts. Apart from history and thermal springs, the area is well-known for Mount Osogovo and the Banska River, the latter being renowned for its fertile banks. In Roman times, the area was very well-developed, with thermal spas, intricate mosaics and Byzantian basilicas. The Roman fortress from the 1st Century AD enclosed a former Thracian village. The Hisarlaka Fortress, another notable sight in the vicinity, dates back to the 4th Century AD, and served a strategic purpose during the Second Bulgarian Empire.