town, southwestern Bulgaria. It lies on the margin of a small alluvial basin in the Struma River valley at the foot of the Osogov Mountains. It was known in Roman times as Pautalia, or Ulpia Pautalia. Located on the site of a Thracian fortified settlement, it became an important town during the Roman emperor Trajan's rule but was later badly damaged by barbarian invasions. During the second Bulgarian empire—from 1186 to the 14th century, when a local feudal lord, Constantine Dragash, established a short-lived independent principality—the town was known as Velbuzhd.

Kyustendil has developed from an Ottoman market town into an industrial centre that specializes in carpets and has factories for woolens, fruit canning, vegetable oils, and packaging. Hothouses produce early vegetables. The waters of local mineral springs heat the hothouses and serve the sanatoriums, which are popular as resorts. The town is the centre of what is called “Bulgaria's orchard”—extensive orchards and vineyards surround it—and a fruit-growing-research institute is located there. Pop. (2004 est.) 47,602.