Pope John Paul II, proclaiming the start of "spiritual preparations" for the 500th anniversary of Christopher Columbus' voyage to the New World in 1492, arrived at Zaragoza in northeastern Spain today on the first leg of a trip that will take him to the Dominican Republic and Puerto Rico.

The overnight stopover of John Paul -- who was welcomed by King Juan Carlos, Queen Sofia and Socialist Prime Minister Felipe Gonzalez -- was his second visit to Spain in just under two years and was made at the personal request of the royal couple.

In Santo Domingo, the Dominican capital, the pope will preside over a meeting that will inaugurate the Roman Catholic Church's observation of the 500th anniversary of the introduction of Christianity into the Western Hemisphere. He also is to address Latin American bishops on the issues surrounding liberation theology, a controversial movement that seeks a politically committed role for the church in fighting poverty in the Third World.

On Friday, the pope will stop in San Juan, Puerto Rico, before returning to Rome.

In Zaragoza, the pope's first stop was the cathedral, where the Virgin of El Pilar, the patroness of all Hispanic nations, is venerated.

After prostrating himself before the tiny blackened statue of the virgin, who according to legend appeared to St. James the Apostle in 40 A.D., the pope addressed a crowd of relatives of the 18,500 Spanish missionaries now in Latin America.

The warm reception for John Paul raised again the issue of the continuing pull exerted by Catholicsm over Spaniards despite studies suggesting that fewer than a third call themselves churchgoers and that Spain is rapidly becoming a "post-Christian" society.

As in his nine-day visit in 1982, the pope proved to be a highly popular figure. Speaking in fluent, though accented, Spanish, he recalled, in a short speech at the airport, that two years ago he had entreated the Spanish people: "Live up to your religious roots."

In the two years since, a Socialist government, headed by Gonzalez, an agnostic, has taken office and has often clashed with the bishops. Controversy has centered on legislation to lift bans on abortion and on moves to increase government control over schools run by religious orders that receive public funds.

Gonzalez and his government, as much as the bishops themselves, have steered clear of open conflict.