Puteoli, the modern city of Pozzuoli, was built by the Greeks and became a Roman colony in 194 BC. The port of Puteoli became after a while the official port of Cumae and was connected with Cumae by a canal.
For a long time Puteoli was the largest transit port of Rome. It received grain ships from Alexandria and ships with other cargoes from the whole Roman empire. It was also the biggest harbour for goods from Campania. Of great importance was the export of local volcanic sand (today called pozzolana) that was used in mortar for concrete that could even set under water. The role of Puteoli as main port of Rome was slowly taken over by Ostia and Portus in the first and second century AD.
Above Puteoli the Solfatara ('sulfur earth') is worth a visit. It is a shallow volcanic crater continuously emitting jets of steam with sulfurous fumes. It illustrates the widespread volcanic and seismic activity in the area, the eruptions of Mount Vesuvius, the sinking of Roman ruins below sea level.