(Sited from www.catholiceducation.org)The Miracle of Lanciano is the first, and many believe the greatest, Eucharistic Miracle of the Catholic Church! This miracle occurred in the 8th Century in Lanciano, then known as Anxanum. There the monks of St. Basil had established a monastery under the patronage of St. Longinus, believed to be the centurion at the crucifixion who proclaimed (Mt 27:54) "Truly, this was the Son of God" and pierced the side of our Lord with his lance. (Jn 19:34)
One day, a monk was offering the Holy Sacrifice of the Mass. He had been plagued by doubts about transubsantiation/whether our Lord was truly present in the Holy Eucharist. This time, when the monk pronounced the words of consecration, the host was miraculously changed into flesh and the wine into blood.
The monk was awestruck! Weeping joyously, he regained his composure and called the congregation around the altar and said, "O fortunate witnesses, to whom the Blessed God, to confound my unbelief, has wished to reveal Himself visible to our eyes!" Those who witnessed the miracle spread the news throughout the land.
Shortly after the occurrence, the Blood coagulated into 5 globules of different sizes, but the Flesh remained the same. Catholic Church authorities have certified the Miracle.
In 1258, the Franciscans built a new church under the patronage of St. Francis of Assisi to replace the decaying church of St. Longinus. The Monstrance with the Eucharistic Miracle remains at this basilica under the care of the Franciscans. It is available for adoration and viewing every day.