''It will be the biggest religious activity in Cagayan Valley in recent history,'' said Archbishop Diosdado Talamayan.

The shrine, Talamayan said, was built by Spanish missionaries to pacify the Itawits or Itawes, the native settlers of western Cagayan, in 1604.

It will be the first basilica minore in the region and the fourth in the Philippines. The rites will be officiated by Antonio Maria Cardinal Javierre Ortas, the Vatican's representative.

Historian Ed de Rivera Castillet, in his book ''Cagayan Province and Her People,'' said the Itawits killed Spanish settlers after the Spaniards abused their friendship.

The account showed that the natives resented the settlers' requirement for them to wear hats, shoes and formal dress during holidays.

In 1604, a Spanish missionary succeeded in pacifying the Itawits by transferring the Image of Santa Maria del Rosario from Nueva Segovia (now Lallo town), the seat of the bishopric, to Piat.

Fray Julian Malumbres O.P., in his book ''Historia de Cagayan,'' said the statue of the Our Lady of Piat was fashioned by an obscure sculptor in Portuguese Macao in 1600.

Cagayan Valley residents have been awed by the miracles performed by the Lady of Piat, said Talamayan.

Historical accounts showed that the Lady saved Cagayanos from the 1624 drought. During that time, the people plowed and planted their fields three times, but in as many times, the plants dried up.

Seeing the plight of the Cagayanos, Fathers Francisco de Santa Ana and Andres de Haro, parish priests of Piat and Tuao towns, respectively, led the people in a public rogation. From their pulpits, the priests exhorted the people to go to confession and receive Holy Communion.

The people followed and on the very same night, a heavy downpour fell on their parched farms.

Since then, tourists and pilgrims have been visiting the shrine in Piat to seek the Lady's help in prayers and rarely have their requests been unanswered.

The Our Lady of Piat's miracles are now recorded in the basilica's stained glass windows.

Some of the activities lined up for the shrine's elevation into a basilica include a medical mission for poor Cagayanos. Cagayano doctors and members of the Rotary and Lions clubs will spearhead the medical mission in Cagayan for two weeks.

A weeklong special prayers and services will be held in 29 parishes in the province. These will be highlighted by a Marian choral contest at the St. Paul University in Tuguegarao.

A Santacruzan sponsored by the Department of Tourism will also be held.

A grand procession of all the images of patron saints and the Marian will be held from Barangay Maguiling in Piat to the basilica.

A cultural show on the documented miracles of the Virgin of Piat and the inauguration of the Our Lady of Piat Museum are also scheduled.

Talamayan said the Catholic church ''Christianized'' the meaning of basilica (Greek term for ''for people'') to be a ''gathering place for assembly of God.''

The four papal churches in the world are all in Rome. These are the St. Peter's Basilica, the Basilica of St. John, which is the cathedral of the Pope and the head of all churches, the Basilica of St. Paul, and the Basilica of Santa Maria Maggiore.

The basilica minore of Piat is the first in Cagayan Valley. It will join the ranks of other basilicas in the country. These are the Manila Cathedral or the basilica minore of the Our Lady of Immaculate Concepcion; the basilica of the Our Lady of Charity in Agoo, La Union; and the Basilica of the Santo Niño in Cebu City.