Monastery housing baroque church with ceiling frescoes and a marble altar. From 1866 the building houses a museum.
Along with Castel Sant'Elmo that stands beside it, this is the most visible landmark of the city.
The monastery was finished and inaugurated under the rule of Queen Joan I in 1368 and it was dedicated to St. Martin of Tours.
During the first half of the 16th century it was expanded and became essentially the structure one sees today. In the early 19th century, under French rule the monastery was closed and was abandoned by the religious order. Today, the buildings house the National Museum of San Martino.