Given the volatile atmosphere awaiting Manchester City in the cavernous Stadio San Paolo, it is perhaps no surprise to discover that Napoli's intimidating home ground is built on volcanic rock in an area known here as Campi Flegrei.
The 60,000-capacity venue is the third biggest in Italian football after Milan's San Siro and the Stadio Olimpico in Rome, but arguably the most hostile.
It will certainly play a part when Pep Guardiola's side attempt to qualify for the Champions League knockout stage with either a win or draw in Group F on Wednesday night.