During the laying of foundations of the plant at the countryside of Kostadin fountain close to the National Archeological Site Deultum – Debelt are found antiquity objects for daily use, ornaments and decorations, religious objects. All this is a testimony for dynamic life and civilization in the region. During the archeological excavations on the territory of metallurgical plant are discovered medieval basilica built in 9th century and ancient customs. More than 64 lead seals are found. Three of them belong to the Boris I, Khan of Bulgaria (852–89), known with the baptism in the Orthodox faith (864).