Not far from the Celije Monastery, in the canyon of the Gradac River, an archaeological site has been found, which archaeologists believe dates back to antiquity. It is a small fortification, a watchtower, dating from the 3rd or 4th century. The site was discovered ten years ago, and research and excavation started five years ago as part of the project "Valjevo County in the Middle Ages," funded by the Ministry of Culture.