The good news from the Eternal City in this extraordinary Holy Year declared by Pope John Paul II is that the number of officially confirmed miracles is going up. The bad news is that the buildings of ancient Rome are falling down, and the expected tourist boom has not materialized.

Not only has the number of tourists declined, but, travel agents say, "the quality" has deteriorated as well. The city, they sniff, is crammed with busloads of pilgrims on package tours who stay for about as long as it takes to receive a papal indulgence and throw three coins in the Trevi fountain. But the big spenders--the Americans and Arabs--haven't shown up.

In a way, one can see why. Rome remains a beautiful city, but it has lost the glamour that was associated with la dolce vita of the 1950s and 60s. The film stars don't parade down the Via Veneto anymore for fear of being kidnaped. And the atmosphere of fun and frivolity that used to be so characteristic of Rome has been blunted by the rise in violent crime and economic austerity. ONCE ONE OF the world's exclusive playgrounds, the city is becoming somewhat tacky. Surrounded by Bernini's columns, St. Peter's Square is as breathtaking as ever. But the crowds that turn out to see the pope appear at his balcony on Sunday look more like football fans than pilgrims. They wave banners and cheer wildly when the pontiff addresses them in different languages.

Most disappointing of all from the tourists' point of view is that many of Rome's most famous ancient monuments can no longer be seen. The Pantheon, built in 27 B.C. to celebrate Rome's victory over Cleopatra of Egypt, was closed in March when a piece of falling masonry injured a German tourist. The statue of Marcus Aurelius has been removed from Campidoglio Square because of "bronze disease," caused by pollution. And many of the buildings in the Roman Forum are obscured altogether by a green protective covering. THE POPE'S proclamation of 1983 as an "extraordinary" Holy Year, in commemoration of the 1,950th anniversary of the crucifixion, caused some surprise here in view of the fact there was a Holy Year as recently as 1975. Normally the Roman Catholic Church only celebrates such jubilees once every quarter century.

Some of the Vatican's disappointment at what has so far been a poor public response to the Holy Year could, however, be offset by the increase in miracles that was disclosed in a recent magazine interview by Cardinal Pietro Palazzini. The cardinal, who at 71 heads the Congregation for the Sainthood, said the Vatican is at present examining a dozen or so miracles--mainly cases of faith-healing.

Palazzini, who gained a reputation for fervent anticommunism in the 1950s, noted that the upward trend in miracles is also evident in the Soviet Bloc. He mentioned the case of Poland, the pope's homeland, which has produced Roman Catholicism's latest saint, in the person of the Rev. Maximilian Kolbe, and two candidates for beatification. Current Vatican regulations require proof of four miracles before someone can be declared a saint and two before the intermediary step of beatification.

Cynics, however, have suggested there could be another explanation for the increase in miracles. When Cardinal Palazzini was appointed to his present job by the pope in 1980, he relaxed the rules. Where once a special congregation at the Vatican was charged with recommending would-be saints, today this task has been entrusted to local bishops. This has had the effect of accelerating the cumbersome procedures, but also of multiplying the number of candidates.

It is one of history's ironies that modern civilization is causing almost as much damage to Rome's classical buildings as the deliberate destruction of the Dark Ages. Pollution from cars and central heating systems has triggered a chemical process that literally turns marble into chalk. Delicately carved sculptures that survived the ravages of the Goths and Visigoths are now disappearing. THE ROME CITY COUNCIL has taken some steps to alleviate the problem such as closing part of the traffic circle around the Colosseum and a road that used to cut right through the Forum. But a much more ambitious plan to transform the center of Rome into an archeological park has been held up by bickering among politicians in the national government and a dispute over funds.

The process of chemical devastation has been slowed down by hiding the monuments behind scaffolding. This protects them from the rain that was the catalyst that turned the sulphur dioxide in the polluted air into the destructive sulphuric acid that ate away at the surface of the marble.

Most experts believe, however, that the only long-term solution is a radical transformation of the living and working habits of Romans and visitors to the city. The superintendent of Roman monuments, Adriano la Regina, has proposed a project that would involve relocating the offices of thousands of government bureaucrats to the outskirts of town. The city's historic core would be closed to traffic altogether and the Via dei Fori Imperiali, the great thoroughfare connecting old and new Rome, would be dug up.

Archeologists believe that many treasures are hidden under the road--from the classical period onward.

Preliminary work on the project should have started this spring but was held up by the opposition of the culture minister, who said that funds earmarked for "restoration" could not be used for "excavation." It is now uncertain when, or even whether, the final approval will be given.

La Regina deplores the fact that his project has become bogged down in the mire of Italian politics.

"But when you have a government crisis every nine months, what can you do?" he asks with more than a hint of frustration in his voice.