Civil engineering is a professional engineering discipline that deals with the design, construction and maintenance of physical and natural built environment, including works such as bridges, roads, canals, dams and buildings. Civil engineering is the oldest engineering discipline after military engineering, and it was defined to distinguish it from military engineering. It is traditionally broken into several sub-disciplines including environmental engineering, geotechnical engineering, structural engineering, transportation engineering, water resources engineering, materials engineering, coastal engineering, surveying, and construction engineering. Civil engineering works are carried at all levels: in the public sector from municipal through to federal levels, and in the private sector from individual homeowners through to international companies.