The Vienna of Christmas Eve could be a planet or two away from the bustling, summertime Vienna that most of the hundreds of thousands of visitors who come each year to the captivating capital on the Danube get to know.

By Dec. 24, the waves of brightly clad Americans on package tours have long since dwindled to a purposeful few and the swarms of exuberant young backpackers have completed their cyclonic sweeps through Europe for another season.

The first soft snow may have fallen in the city -- whose winter climate resembles Washington's. The wind has turned cold and the days have become markedly shorter, with the sun setting well before 4 p.m. at this far eastern edge of the European time zone.

Now imagine the soft strains of "Silent Night" -- written in a country village a few hours' drive to the west -- coming from a storefront speaker, beckoning the passerby to sample a dazzling array of marzipan and decorated gingerbread -- called lebkuchen -- and other holiday treats such as stollen, or guglhopf, the sweet Christmas coffee cakes.

A Christkindl Markt -- a colorful market of stalls and kiosks, selling Christmas gifts, tree ornaments and other holiday decorations -- has taken over the Rathaus Platz, the square in front of Vienna's imposing, neo-Gothic town hall, and elaborate, hand-carved mangers decorate store windows in the narrow side streets of the compact Old City.

Viennese women in long fur coats and fluffy fur hats, and Viennese

men in loden greatcoats of green or gray, or felt jackets with red trim, complete their Christmas errands, bustling past posters announcing special holiday performances of the Vienna Boys Choir, the State Opera and the Vienna Philharmonic, as well as midnight masses at the vast 13th-century St. Stephen's Cathedral and other downtown churches.

If the chill gets too deep, or time weighs heavy, one can warm up or rest by popping into Demel, arguably the world's prototypical pastry shop -- or one of the dozens of lesser coffeehouses and konditoreis, for a sweet and coffee, or a light lunch. The summer crowds are gone from these, and there is elbow room once again in the venerable, cavernous wine cellars as well, where the warmth comes in viertel size.

While summertime Vienna seems to belong to the tourists -- as many Viennese leave their city for the cooler mountains or seashore -- the fabled Austrian capital belongs to its own at Christmas. The season is a time for family and friends but also a rewarding period for visits by outsiders who want to share the experience of a holiday marked by a mixture of centuries-old traditions and late 20th-century amenities.

While living in Vienna for three years, I came to look forward to the changed rhythm that comes to the city each winter. A heritage dating back to pagan rituals before the arrival of the forces of the Roman Empire -- and of Marcus Aurelius, who died in Vienna -- and heavily influenced by centuries of Roman Catholicism has given Vienna a rich foundation for its December and January festivities.

It all provides opportunities for entertainment, feasting, celebration and spectacles -- both secular and religious -- that can make Christmas and New Year's a memorable time to visit the still enchanting former capital of the Austro-Hungarian Empire.

Advent -- the four weeks preceding Christmas -- begins the holiday buildup, with a succession of special days such as Dec. 5, when Krampus, a fierce-looking evil spirit, punishes bad children in a spirit of fun, and Dec. 6, when St. Nicholas rewards the good boys and girls with candy and gifts. Both Krampus and St. Nicholas can be found in doll and pastry form throughout the city at this time.

Christmas Day, of course, is the high point of the season, but far from the end of it. Dec. 26, St. Stephen's Day, is a day of pageantry and religious ceremony, especially at the cathedral in the middle of town that bears the saint's name, and it marks the beginning of Twelve Nights. This period includes Sylvester, as New Year's Eve is known, and New Year's Day, and ends with Epiphany -- all occasions for further merriment. Then begins Fasching, the pre-Lenten carnival ball season.

The Austrian capital seems to take on a special glow and warmth in the Christmas period, with streets and stores glitteringly decorated, special holiday musical and stage performances and traditional seasonal menus in restaurants all contributing to the seasonal gemu tlichkeit.

The renowned Vienna State Opera, grandly situated on the city's broad and elegant Ringstrasse, and its operetta cousin, the Volksoper, both shuttered during the high tourist months of July and August, are in full cry in the winter. The Vienna Boys Choir performs regularly at the chapel in the Hofburg, the vast downtown palace of the Hapsburgs. The Vienna Philharmonic gives weekly concerts, plus an internationally televised New Year's spectacular, and the Vienna Symphony plays. The Lipizzan stallions of the Spanish Riding School cavort for the public in the Hofburg on Sundays -- but only through Dec. 13, after which they suspend appearances until February.

Church music is especially attractive at Christmas time. Many of Vienna's ornate Roman Catholic churches perform masses by Haydn, Mozart, Bruckner and others, with orchestra and professional soloists. Among my favorites for these performances were the Augustinerkirche, at Josefsplatz by the Hofburg; the majestically baroque Karlskirche a short distance south of the State Opera; the Minoritenkirche, near the Ballhausplatz; and the tiny, jewel-like Maltese Church, on Kaerntnerstrasse, the Old City's main shopping street.

The churches post their music schedules at the door, and weekend schedules for these and other attractions are published in the Friday edition of Die Presse, a leading Vienna newspaper. Most are free of charge -- although the masses sung by the Boys Choir require tickets -- but visitors are expected to respect them as the religious services that they are. (Twice, people visiting Viennese churches with me have been scolded for having their hands in their pockets. "Tell the young man he's in God's house," a scrubwoman once told me sternly, gesturing toward an oblivious friend who spoke no German.)

A word of warning: If you're in Vienna on Christmas Eve, plan on a quiet time. Stores, restaurants and theaters shut down, though hotels do not, and most Austrians mark the evening with family gatherings in their homes, followed by attendance at midnight mass. St. Stephen's draws up to 10,000 worshipers and spectators for its splendid service.

Christmas Day is a time for feasting in Vienna. Restaurants are open again, with festive decor and seasonal menus that center on such high-cholesterol dishes as oxtail or marrow soup, roast pork, roast goose and sweetbreads. Boiled beef, veal, trout and roast chicken are a few steps down the caloric ladder. Elaborately prepared carp, boiled or in aspic, and festooned with a colorful variety of accompaniments, is a traditional Central European Christmas dish. (A friend told me that, when she was growing up in Czechoslovakia, the bathtub in her family home was always reserved for fattening the Christmas carp in the last few days before it was turned into a meal.)

Afterward comes another wave of gorgeous calories, in the form of pure'ed chestnuts, apple strudel, poppyseed cake, hazelnut torte, dessert crepes -- all smothered in powdered sugar or whipped cream (schlag) -- or that most gluttonous of Viennese desserts, the germknoedel (pronounced gairm-kuh-nerdel), a fist-sized lump of sweet dough, cooked and served under a coating of poppyseed, powdered sugar and melted butter.

A week later, New Year's Eve and New Year's Day are celebrated with recharged pomp and panache. The Vienna Philharmonic, in the Musikverein building, and the Vienna Symphony, in the Konzerthaus, give concerts both days. The State Opera stages its traditional sparkling performance of "Die Fledermaus," with real Champagne for the drinking scenes, on New Year's Eve, and repeats it again the next night -- without alcohol. The Imperial Ball, inaugurating the series of hundreds of Viennese balls that will be held before Ash Wednesday, takes place in the Hofburg on Dec. 31.

Other operas scheduled for late December and early January this winter include "Die Meistersinger," "Rusalka," "The Valkyrie," "Tannha user" and "La Bohe`me."

If you want to remember your Vienna Christmas in the years to come, load up on ornaments and other seasonal items and take them home. Advent wreaths and calendars (with doors to open for each day of the pre-Christmas countdown) are widely sold, as are distinctively Old World Christmas cards. Creches, religious figures and tree ornaments -- of handcarved wood, hammered tin, blown glass, woven straw, even marzipan -- can be bought at the Christkindl Markt and many downtown shops, or, less expensively, at drug stores (drogeries) and the ubiquitous Tabak kiosks that sell cigarettes, magazines, streetcar tickets and sundries.

A final suggestion: If you still have some money -- and room in your suitcase -- buy a packaged Sachertorte at the Sacher Hotel or a wooden-boxed pastry at Demel and, when you get home, whip up the thickest cream you can find, douse whatever you bought with it and recreate, for one terrifically high-calorie moment, your Christmas in Vienna.