The Torre Flavia oasis extends along the coast between the towns of Ladispoli and Cerveteri. It is one of the now rare marshy areas of the Lazio coast, it represents the last remnant of the Campo di Mare Marsh, a system of coastal marshes and salt marshes. The territory appears as a succession of small depressions that fill with water seasonally, thanks to the surfacing of the underlying coastal aquifer, the contribution of fresh water from the hinterland and winter rains. The varying salinity of the water has generated vegetation typical of brackish areas, such as glasswort, the symbol of the oasis. The innermost area, marshy for much of the year, with less salty water, is covered by common reeds and water lilies. The fauna finds its maximum expression in birds, which find here the ideal environment both for wintering and for stopping during migration. Torre Flavia is named after Cardinal Flavio Orsini who built it in the early 1500s on the foundations of a previous medieval fortress and near a Roman villa, to counter Saracen raids. The tower has a square plan with a sloping base. The current state of the Tower is the result of bombings during the Second World War and the process of marine erosion. Until the 1930s, Torre Flavia was still located on the coastline; the progressive coastal erosion has gradually isolated the remains of the building.