Natural bitumen, due to its chemical properties, is highly stable, durable, flexible, water-resistant, convertible, etc. That is why in ancient times people used bitumen as a waterproofing and binding material. Bitumen was used to cover water and grain storage facilities, the walls and floors of palaces, and to cement stone-paved city streets.  Aristotle and Hippocrates, who lived four centuries BC, wrote about bitumen deposits. Historical documents from the 8th century contain information about the existence of solid bitumen deposits in Baku and its environs.