Campos Flégreos
Solfatara () is a shallow volcanic crater at Pozzuoli, near Naples, part of the Phlegraean Fields () volcanic area. It is a dormant volcano, which still emits jets of steam with sulfurous fumes. The name comes from the Latin, "Sulpha terra", "land of sulfur", or "sulfur earth". It was formed around 4000 years ago and last erupted in 1198 with what was probably a "phreatic" eruption – an explosive steam-driven eruption caused when groundwater interacts with magma. The crater floor is a popular tourist attraction, as it has many fumaroles and mud pools. The area is well known for its bradyseism. The vapours have been used for medical purposes since Roman times.