The town of Kostenets is situated in the foot of Rhodope mountain, near Belovo and Septemvri.
The region was populated as early as the Bronze Age and the Iron Age. It was inhabited by the Thracian tribe Besses during the first millennium BC. At the end of c.1 and the beginning of c.2 AD, the territory of the present-day Kostenets municipality was part of the Serdica Province of the Roman Empire.
The settling into the present-day municipal centre Kostenets started in 1884 with the building of the Belovo - Vakarel railway as a part of the Sofia - Istanbul route. The new settlements'' expansion hastened with the building of a factory for safety matches in 1901 and of a paper mill in 1907. In 1964, three settlements - Kostenets Banya, Momin Prohod and Momina Banya - were merged into the town of Kostenets.
There are 36 preserved burial mounds, 20 mound necropolises, remains of 11 antique settlements and settlements of the Bronze Age and the early and late Iron Age, 6 Roman settlements and 8 late medieval settlements in the region of Kostenets.
The Trayanovi Vrata Fortress is a valuable monument of the Roman age, and of the First and the Second Bulgarian Kingdom. There in 986 the Bulgarian king Samuil defeated the Byzantine emperor Vasilius II.
The spa resorts Villas Kostenets, Pchelinski bani, and the village of Kostenets are near the town. Very beautiful is the Kostenski Waterfall, located near the village of Kostenets and depicted by the eminent Bulgarian writer Ivan Vazov. Only 28 km west of the town of Kostenets is situated the winter resort of Borovets.