MILAN — Imagine moving the Colosseum into a skyscraper.

The thought of Italy’s most famous opera house, La Scala, being replaced — even temporarily — by a brand new building on the outskirts of Milan is just as disconcerting for Italians, who consider the 18th-century theater a hallmark and an almost sacred institution.

But to compare the two is like looking at apples and oranges — as neoclassic and stately as La Scala is, its replacement, the new Arcimboldi Theater, is exponentially postmodern and massive.

For the next three years, La Scala will undergo extensive renovations, and the lyrical seasons will find a new home at the Teatro degli Arcimboldi, located in the Bicocca area, a half-hour’s commute from the center of Milan. It is named after a medieval noble family at the court of the Sforza dukes, who built a country villa on the site in 1450, named it the Bicocca and decorated it with magnificent frescoes. The most famous Arcimboldi, the painter Giuseppe, is known for his bizarre portraits that show human shapes made of fruits, flowers and plant combinations.

The Arcimboldi Theater was built at a cost of $39 million in 27 months — a record by Italian standards — and was inaugurated this past weekend with Giuseppe Verdi’s “Traviata,” conducted by Riccardo Muti. Designed by architect Vittorio Gregotti, it is the largest new theater in Italy and accommodates 2,400 people, with two levels of stalls and two rows of galleries.

“I wanted to create a sensible, simple theater,” said Gregotti. “Its main quality is that it is ‘normal’ — what you would expect from a theater,” said the architect, whose recent projects include the city’s Malpensa airport and Lisbon’s Belem theater.

Accordingly, Gregotti said, he didn’t try any “adventurous experiments.” Its foyer and a fan-shaped hall are covered with lacquered red maple wood in the same technique used to dye violins, while the architect also recovered several 19th-century decorations from La Scala’s scenographic archives for display. La Scala’s original burgundy velvet curtain also was moved to the Arcimboldi.

Several elements of the new theater were created in deference to the famed La Scala, an effort that seems to have placated many concerns among the Milanese. Some critics here are embracing the building.

“[The Arcimboldi’s] acoustics are far better than the Scala’s,” said Paolo Isotta, musical critic of Italy’s daily paper, Corriere della Sera. “The [sound] balance between orchestra and stage is perfect,” said Isotta, noting that the singers are not overshadowed by the music.

Daniel Commins, the acoustics expert who worked with Gregotti on the project, said mobile glass panels were installed to act as sound deflectors as well as lighting screens for the halls. “A complex scansion of the plaster ceiling guarantees the best acoustics quality.” The large glass roof in the foyer was the most difficult element to carry out architecturally because of the different width and angle of each window that makes up this structure, he said.

Outside, the sand-colored exterior is finished in clear plaster with a base in black granite, and opens onto a large square. “I think the square in front of the theater is very successful because of the long perspective,” said Alessandro Palmarini, architect of Studio Longo here, who expressed a favorable opinion of the project. “The building is enhanced by the expanded opening of the square,” he said. Palmarini also said that the theater was well integrated with its surroundings and that the curved front of the building made its function recognizable.

Steel sculptures from artist Giuseppe Spagnulo are centrally placed in the square. “The material is a tribute to the industrial origins of the area,” said Gregotti.

Designer and architect Gianfranco Ferre, present at the inauguration, said he was impressed by the theater for a number of reasons.

“The architecture is rigorous, linear and elegant for the recovery of an area that has a proud and grand history,” he said. “It is fundamental, however, to get used to it.

The Bicocca is not La Scala, nor is it its futuristic substitute. It’s something beautiful, valid and important, per se.” The Bicocca, an area that covers about 1 million square feet that is owned by tire manufacturer Pirelli, has in recent years been redeveloped and turned into a new urban center. Most of the original industrial factories have been torn down, and the area now lodges departments of the State University, research centers, branch offices of multinationals such as Siemens, Johnson & Johnson, Reuters, Deutsche Bank, and Compaq, and roughly 4,000 residents.

Pirelli sponsored the new theater, investing $25 million in the project.

But the decision to locate the theater in this area has been cause for debate, with many opera devotees worried about the distance from the center of Milan. Gabriele Albertini, mayor of Milan, said shuttles have been arranged from the center of the city and noted that the theater is accessible by train and subway. He added that when La Scala reopens in three years, the Arcimboldi will lodge other cultural events and shows and will also be open to European artistic happenings.