Saint Januarius' dried blood is stored in 2 ampoules, held since the 17th century in a silver reliquary between two round glass plates. The relic is famous for the reputed miracle of the annual liquefaction of his blood, which, according to legend, was saved by a woman called Eusebia just after the saint's death. Thousands of people assemble to witness this event in Naples (urbs sanguinum) 3 times a year. Disbelievers credit this tri-anual happening to a medieval Neapolitan alchemist.