18. The dried blood of St Januarius still liquefies three times a year.
We know very little about St. Januarius (d. c.305), Bishop of Benevento, except that he was one of many early Christians executed by the bloodthirsty Emperor Diocletian. Diocletian originally planned to feed him to bears, so he was lucky only to be imprisoned and beheaded. According to legend, a woman named Eusebia had the foresight to collect the blood gushing from his neck in a couple of phials, which are now cherished relics in Naples, which purchased them in the 5th century. You’d think the blood would be dry after over 1700 years, right? Wrong (sort of).
The blood of Januarius is usually dry, but it miraculously liquefies every year on his three feast days. On these days (above), the phials in their ornate reliquary are held aloft while prayers are recited in the Cathedral of Naples. Eventually, the crusty contents liquefy and bubble with great enthusiasm, to the amazement of the congregation. The thrice-annual miracle remains one of the most controversial events in the Catholic calendar. Despite many ingenious attempts to expose the miracle as a hoax, nothing has been determined, since the Cathedral has understandably no interest in giving the phials up for scientific analysis.