Castellammare di Stabia , city (1991 pop. 68,720), in Campania, S Italy, on the Bay of Naples. A summer resort and spa, it has thermal mineral springs that have been used since Roman times. It is also a commercial and industrial center, with shipyards founded in 1783. Manufactures include food products, paper, and cement. The city was built on the site of Stabiae, a favorite Roman resort, which was buried in the eruption of Mt. Vesuvius in A.D. 79. The royal villa, Quisisana (built 1310, rebuilt 1820), is now a hotel.