The Certosa di San Martino is a former monastery complex, now a museum, in Naples, southern Italy. Along with Castel Sant'Elmo that stands beside it, this is the most visible landmark of the city, perched atop the Vomero hill that commands the gulf. A Carthusian monastery, it was finished and inaugurated under the rule of Queen Joan I in 1368. It was dedicated to St. Martin of Tours. During the first half of the 16th century it was expanded.