The Campi Flegrei bradyseism — ground uplift and seismic swarms through 2023 to 2025 — is an ordinary due-diligence item in Bagnoli, Fuorigrotta and Pozzuoli, not folklore. Ask for the structural assessment and the civil-protection zoning.
Building-permit history matters more here than in any other Italian city on this list. Unpermitted works and pending condono applications block a clean deed; the notaio will surface them, but late and expensively.
Chiaia, Posillipo and the Vomero ridge carry a durable premium. The centro storico is UNESCO-listed, dense and, in parts, structurally tired.