The Campi Flegrei are a large volcanic field enclosing a large area west of Naples that includes Bacoli, Monte di Procida, Pozzuoli, Quarto and Naples (districts of Agnano and Bagnoli).

Although located outside the original crater, Campi Flegrei also includes Ischia, Vivara and Procida islands that share a part of the mainland volcanoes geological history. What is more, research has identified other numerous craters sunk in the sea of the Gulf of Pozzuoli, making even more striking the story of the birth of this unique site in the world.