Kyustendil (Bulgarian: Кюстендил, historically Велбъжд, Velbazhd) is a town in the far west of Bulgaria, the capital of Kyustendil Province, with a population of 58,059 (2005 census). Kyustendil is situated in the southern part of the Kyustendil Valley, 90 km southwest of Sofia. It was named after the medieval lord of the surrounding region, Constantine Dragaš.

A Thracian settlement was founded at the place of the modern town in the 5th-4th century BC and the Romans developed it into an important stronghold, balneological resort and trade junction called Pautalia in the 1st century AD.

The Hisarlaka fortress was built in the 4th century and the town was mentioned under the Slavic name of Velbazhd (Велбъжд, meaning "camel")[1] in a 1019 charter by the Byzantine Emperor Basil II. It became a major religious and administrative centre.