lowland plain surrounding the city of Rome in Lazio (Latium) regione, central Italy. Occupying an area of about 800 square miles (2,100 square km), it is bounded on the northwest by the Tolfa and Sabatini mountains, on the northeast by the Sabini Mountains, on the southeast by the Alban Hills, and on the southwest by the Tyrrhenian Sea. Abandoned to marshes and malaria in the European Middle Ages, the district was transformed by major reclamation works in the late 19th and early 20th centuries and now supports cereals, fodder, fruit and vegetables, and livestock. Uncontrolled building development and the abandonment of many small farms were changing the once purely agricultural character of the Campagna in the late 20th century.