Built in the 18th century, it is the main church of Naples. It is widely known as the Cattedrale di San Gennaro, in honour of Saint Januarius, the city's patron saint. It was built on the foundations of two palaeo-Christian basilicas, whose traces can still be clearly seen. Underneath the building, excavations have revealed Greek and Roman artifacts. The Cathedral is famous for Miracle of the Blood, a recurring miracle taking place on the first Saturday of May and September 19th every year. During the ritual an ampull containing the old dried out blood of Saint Januarius is brought out and stirred; and miraculously liquefies. According to legend, disaster will befall Naples if the blood fails to liquefy.