Costain Group PLC operates as an engineering and construction company in the United Kingdom, Spain, and internationally. The company operates in three segments: Civil Engineering, Building, and Oil, Gas, and Process. The Civil Engineering segment provides civil engineering services in water, highways, rail, marine, and nuclear sectors. The Building segment undertakes projects in various sectors, including education, healthcare, and retail. The Oil, Gas, and Process segment provides engineering services for new facilities and revamps, including conceptual design studies, front end engineering design, and engineering procurement and construction. The company also provides property development services in Spain, which include residential and leisure complexes development. Costain Group also provides waste water and geotechnical services. The company was founded in 1865 and is headquartered in Maidenhead, the United Kingdom.