THE THREE ROMES by Russell Fraser (Harcourt Brace & Jovanovich: $15.95; 352 pp.)

Though the notion of Three Romes is at least five centuries old, the tenuous linkage had all but lapsed, submerged in a welter of glaringly obvious differences. Intrigued by the idea that Moscow, Constantinople and Rome may still have crucial points in common, Fraser attempts to revive a connection among the three cities; “each one desirous of ruling the world and establishing the kingdom of heaven on earth.” Conceding the three now diverge radically in “their understanding of man’s nature and business,” the author takes the dual challenge as the basic premise for a book that often veers off course to become a highly personal, reflective and idiosyncratic diary.

Visiting Moscow, Istanbul and Rome in turn, heavily salting his contemporary travelogue with historical fact and anecdote, the journal fits somewhere between straightforward history and practical guide--a book to put you in the appropriate emotional and intellectual mood for each place. Like Lawrence Durrell’s “Reflections on a Marine Venus” or Paul Theroux’s lively records of his explorations through Patagonia and around the British Isles, “The Three Romes” makes fine supplementary reading for those who already have the fundamentals well in hand.

In the middle of the 15th Century, Philotheus, a Russian monk, wrote to the czar with confidence that Moscow would endure long after prior claimants to the title of Eternal City were forgotten. “For two Romes have fallen, but the third stands, and a fourth shall never be.” Even though many observers have since vigorously advanced the idea that America might be the ultimate Rome, Fraser neither alludes to this suggestion nor considers it, confining his investigation to the ancient and medieval trio--for his purposes, more than enough.

While his intent seems academic, Fraser’s style is relaxed and informal, a subjective approach that meanders and rambles around the fragile theme. Seduced and distracted by the urgency of contemporary sights and sounds, Fraser still manages to keep the basic idea in sight, with perspective shifting from day to day. If modern Istanbul seldom seems to bear much relation to ancient Rome or contemporary Moscow to either, Fraser’s impressions are acute and arresting in themselves. We meet his colleague Bogdonov, a professor of English and journalism at Moscow University, who swims all winter long in the pond underneath the Ostankino TV tower, breaking a hole in the ice and entering the water by ladder for a 30-second lap. The hardy Bogdonov’s cure for the common cold is rubbing vodka on the ankles, a specific he never needs because his biweekly swims preserve him in perfect health. While Bogdonov may not have anything in common with Emperor Justinian, he does enlarge our understanding of “man’s nature and his business.”

Fraser is the best preparation for modern Istanbul one is likely to find, beginning with the airport, where “coal dust on the wooden benches and metalled radiator covers feels like granules of sugar. The smell of burning coal, mixed with tobacco smoke, brings back London in the old days. Fraser can be equally explicit on the glories of ancient Byzantium, few vestiges of which survive today. Those that do, lead the author to some of his more invidious and effective comparisons, in the violence of present-day Istanbul as an inevitable extension of a long and bloody national history. Here, there’s no need to strain for analogy in order to demonstrate the validity of the premise. In Istanbul, anyone can step out of the present merely by pushing aside the heavy leather curtains at the doorway of a mosque. Once inside, the 10th Century is intact, and “you needn’t know, unless you want to, that the muezzin’s calls to prayer are recorded and amplified.” In this section of the book, Fraser’s technique of dropping random bits of fact into his contemporary narrative seems not only justified but the only sensible way to deal with the deluge of impressions, the hideous and the exquisite as inextricably entwined as the arabesques in the crumbling tiles.

Rome easily survives the author’s ironic overview. There he manages to have fun despite his determination to exploit every resemblance, however remote, between his three locales. Once in the original Eternal City, he’s pleasantly diverted: dining well; relishing a performance of “The Girl of the Golden West” in the Baths of Caracalla; even finding a kind word or two to say about E.U.R., Mussolini’s vainglorious attempt to establish a suburban paradise on the outskirts of Rome. Time has mellowed the once-raw concrete buildings; flowers bloom, the sun shines, the architecture no longer seems anonymous or mean. “Striding into the future, E.U.R. looks brisk and cheerful. Istanbul, shambling towards the future, is Tobacco Road East, modern Moscow a panopticon or prison.” If Fraser hasn’t quite produced the comparative study of civilizations we may have expected from the original hypothesis, he has thoroughly succeeded in placing each of his cities in a novel social and historical context. Along the way, he introduces readers to an extraordinary gallery of ancient villains and modern rogues, all of whom enliven the ambitious enterprise. If “The Three Romes” are not as intimately related as they seemed to the monk of Pskov, the effort to restore the connection is provocative and entertaining.