Basilica of San Francesco — Sacred Hosts of Siena

Why pilgrims come

Encounter the Eucharistic tradition and its surviving evidence

The vast brick Basilica of San Francesco preserves Siena’s most important Eucharistic devotion: consecrated hosts stolen in 1730, recovered three days later, and still venerated by the local Church. The story begins not with a scientific experiment but with sacrilege, communal grief, recovery, and almost three centuries of prayer.

On August 14, 1730, thieves entered the Franciscan basilica and stole a silver ciborium containing 351 consecrated hosts. Siena responded with public acts of reparation. On August 17 the hosts were found in an alms box at the nearby sanctuary of Santa Maria in Provenzano, amid dust and cobwebs. They were identified, reverently cleaned, and carried back to San Francesco in solemn procession.

Because the hosts had been contaminated, the friars did not distribute them in Holy Communion. Over time, however, observers reported that the remaining particles did not show the ordinary corruption expected of unleavened bread. The Archdiocese of Siena describes their continuing preservation as the Eucharistic Miracle of Siena. The number now preserved is smaller than the original 351 because particles were used in examinations and other circumstances over the centuries; the diocesan historical account records 223 remaining hosts.

Catholic Tourist presents the ecclesial facts precisely. The theft, recovery, uninterrupted custody, examinations, and public veneration are documented. The judgment that their preservation is miraculous belongs to the Catholic devotional and diocesan tradition; this page does not substitute an independent laboratory conclusion for the Church’s language or claim that every popular retelling has equal documentary value.

The devotion remains woven into Siena’s living Catholic culture. The archdiocese records an annual commemoration of the August 17 recovery, a Eucharistic day on the seventeenth of each month, the Corpus Christi procession, and a solemn Eucharistic observance in September. Siena’s contrade also pay homage to the Sacred Hosts, joining the city’s civic identity to its Eucharistic memory.

San Francesco itself deserves attention. Founded in the thirteenth century and enlarged into a great Gothic preaching church, it preserves Franciscan history, medieval art, and the memory of St. Bernardino’s preaching in Siena. Yet the right center of a pilgrimage is the Blessed Sacrament. Enter quietly, ask where the Sacred Hosts are exposed or reserved that day, and let the extraordinary story deepen—not replace—ordinary faith in the Eucharist celebrated at every Mass.

Make the Eucharist—not curiosity—the center of the visit. Read the 1730 sequence before arriving, ask where the Sacred Hosts are reserved or exposed, and leave time for silent prayer or Mass.