 Thereafter it shared the fate of the Kingdom of Naples—including the period of Spanish rule of which the 16th-century castle of Charles V, overlooking modern Crotone, serves as a reminder—and its successor, the Kingdom of the Two Sicilies, which was conquered by the Kingdom of Sardinia in 1860 and incorporated into the new Kingdom of Italy in 1861.Crotone's location between the ports of Taranto and Messina, as well as its proximity to a source of hydroelectric power, favored industrial development during the period between the two World Wars.In the 1930s its population doubled.