IT IS DECEMBER, AND THE AIR is a wash of silky light, astringently cool, but sunny enough to allow one to bathe in multiple sensations of warmth. Under white canvas umbrellas in outdoor cafes the beautiful ladies of Rome in their beautiful furs cross narrow ankles; old men read their papers and sigh over remembered pleasures.

On this gorgeous day, the restorers' scaffolding that has obscured the pillars of the Pantheon for a year has been removed; the building that is both prototype (cave) and culmination (temple) of all the buildings on earth is revealed in its amazing beauty. Gorbachev is in Rome talking to the Pope. All the city--Catholic, communist, everyone young and old--is wreathed in smiles. Perfection of weather and of hopes. The Berlin Wall is down. Old shibboleths crumble. There is a spirited will to joy. It is easier than usual to breathe.

"So, are you rejoicing?" I ask Gore Vidal.

"Whatever for?" he asks. "Surely rejoicing is somewhat premature," he says.

GORE VIDAL HAS LIVED DOWN THE STREET from the Pantheon, in the historical center of Rome, since the mid-1960s; he lives in a penthouse with a wraparound terrace in the Palazzo Origo--one of the more resonant addresses in Rome. It belonged to the noble family-by-marriage of Iris Origo, whose life was distinguished by more than graceful prose ("Saint Bernardino of Siena" and "The Merchant of Prato"). She had what Vidal calls a "good war"--protecting her contadini from the Fascists, hiding escaped prisoners of war and Allied soldiers, feeding and housing the poor. Vidal knew Iris Origo and her Anglo-Irish / American family, of course. He knows, as they say, Everyone.

One would think that to be in the proximity of this kind of nobility--not of rank but of heart--would make one contagiously happy. And, as a gloss upon one's happiness, one would, if one lived in the Palazzo Origo, have merely to cross the street to Delfino's, where the Italian version of takeout is purveyed: tender Roman artichokes in satiny olive oil, chicken alla diavolo grilled to golden succulence.

"Does Rome still thrill you?" I ask Gore Vidal.

"I still look at it," he says.

In London, the city from which I have just come, copies of his new novel, "Hollywood" (available next week in the United States), are heaped in the windows of all the bookshops.

"I have no cause to say hosanna," he says.

A CAT CAN'T BE IN HEAT only three weeks after she gave birth, can she?" Vidal asks. A slim, milky-white cat with pale green eyes insinuates herself among our limbs, uttering a mournful cry of dumb lust. The elegant, kittenish creature--who pleases Vidal because, motherhood notwithstanding, she (a Lolita in heat) doesn't look the least like an adult animal--gave birth to a poor thing with a deviated septum. The offspring died in an attempt to suckle, drowned in its own mucus. This week, Vidal, 64, is being operated on for a deviated septum (which makes his face slightly asymmetrical and his voice nasal); he is apparently not a superstitious man.

The drawing room is cold, the coldness of marble, and dark, very dark, though the sun shines brightly on the terrace, and the great chandelier in the dining room is blazing. The only source of heat--the sun seems not to reach this room--are two bouquets of roses, yellow and orange, tightly curled.

The lobby of the Palazzo Origo, which houses a Berlitz school and a school of the dance, is white and Brunelleschi-gray, with bits of antiquity casually built into the walls, Roman-style. Vidal's apartment is achieved by means of an open lift, on which hangs a sign proclaiming that to use the lift is Strictly Forbidden, a sign that everybody--Rome being a place where that which is forbidden is permitted--ignores.

We stand at first on the terrace, with its fresh view of Borromini's St. Ivo alla Sapienzia, its white corkscrew steeple joyously boring into the sky; the dome (from which wild flowers grow) of the Baroque St. Andrea della Valle; the Roman Synagogue (which Vidal has never been in); and two hills, the Janiculum and the Aventine. It is a shock to go from the sunny terrace to the dark living room, like coming out of a movie theater into bright sunlight, only in reverse.

Tapestries, ancestral portraits, a fanciful--kitschy and also rather lovely--mirror from the Royal Pavilion at Brighton, leather, bibelots . I am pleased to sit on a chair frequently occupied, until his death in 1985, by Italo Calvino, of whom Vidal has written with affection and esteem. On the table in front of me are sun-dried figs and walnuts on wooden skewers, made in Vidal's villa in Ravello, on the Amalfi Coast, south of Rome. On the table next to me are a photograph of Paul Newman--faded almost to sepia--with a floppy dead fish in his hand and a bewildered expression on his young face; an unframed colored snapshot of Vidal, a still from the made-for-TNT movie "Gore Vidal's Billy the Kid," in which he played a bit part; and, partially obscured by the colored snapshot, a framed picture of a 1940s kind of woman's face--arched and stenciled eyebrows, dark glossy lips, shoulders framed in some heavy shiny stuff. A dusky male servant pads quietly, making unobtrusive arrangements here and there.

In this solemn Roman apartment, and from this particular chair, it seems natural to speak of writers and writing. "You loved Henry James, no?"

"Oh, yes."

"So is there a contemporary writer you love? I know you loved Calvino." (In fact, Vidal launched the Italian novelist in America in 1973. He reviewed all of Calvino's books in the New York Review of Books, the principal outlet for Vidal's essays since 1964; it was an act of writerly love.)

"That was about it," he answers.