Story of the heritage: The municipality has a rich historical past. Remains from the Bronze Age have been found in the land of Kostenets. Numerous remains and objects testify to a Thracian, Roman and Byzantine presence. According to a local legend, Aaron's summer palace, Samuel's brother, whose mother was from Kostenets, was located south of the Milikini Nivi area in the Kostenets Balkan. Near the village is the fortress ""Trayanovi Vrata"", which played a crucial role in historical events during the Middle Ages. Besides it, on the municipality's territory, there are many remains of ancient temples, Thracian tombs, fortresses, monasteries and buildings. In the past, the population of Kostenets was mainly engaged in iron mining. Forty types of knives were made in the village. There were also 11 madans (iron processing) in the area. Along with these crafts, abadjiystvo (craft fo weaving friezes), tannery, weaving and others developed rapidly. Until the Union, made on September 6, 1885, Kostenets was an important crossroads between Eastern Rumelia and Bulgaria's Principality. After the Liberation, in 1888 the first railway line in the region was completed and put into operation.