Satellite radar interferometry reveals subsidence occurring in an area of about 2 km by 2 km inside the city of Napoli, Italy. The observations show a maximum (vertical) displacement of about 5 cm between 1992/93 and 1996, while the deformation signal decreases between 1996 and 1998. The investigated area is densely populated and has been influenced, between 1992 and 1995, by intensive construction of a new underground railway. These interferometric results demonstrate the high correlation between the observed deformation and the excavation of the tunnels for the development of the underground. ¿ 2000 American Geophysical Union