Pyroclastic soils cover significant parts of the world’s surface, including areas occupied by urban settlements, vital structures and infrastructures. Despite these materials present significant physical and mechanical differences from site to site, posing sometimes severe geotechnical problems, a comprehensive and worldwide accepted geotechnical classification still lacks. The Campania Region, at the centre of which rises the town of Naples, is covered by pyroclastic soils accumulated in the last tens thousands of years as a result of volcanic activity. The examples reported in the paper show that the index, state, hydraulic and mechanical properties of these materials depend on the distance from the eruptive centre and mechanism of deposition. The overall geotechnical framework arising from this review highlights the peculiarities of pyroclastic soils, adding further information to the general knowledge about the properties and behaviour of natural soils.