It’s taken nearly two decades, but the Bronx Museum of the Arts will open an architecturally dramatic new building next week. With more space, a bold new image, and an executive director plucked from the downtown art scene, the museum is poised to be a symbol of the borough’s revitalization.

On Tuesday morning, Mayor Bloomberg and the new executive director, Holly Block, will attend a ribbon-cutting ceremony and preview of the first exhibition in the new building, “Tropicália: A Revolution in Brazilian Culture.”

The building — created in brushed steel and glass by the Miami firm Arquitectonica — doubles the museum’s size. The project cost $19 million, which came from sources including the City of New York, the office of the president of the Bronx, Adolfo Carrión, and the Small Business Administration, through earmarks introduced by Rep. José Serrano.

The South Bronx has experienced a rebirth in recent years, partly because of an influx of artists. Ms. Block, who was a curator at the museum in the mid-1980s, said she has noticed many changes in the neighborhood. “There are lots of new businesses,” she said. “There’s been a big expansion of studio space for artists. There’s a bunch of new parks that have been renovated.”

There are also several galleries in the area, including Haven Arts, the Ironworks Gallery, the Longwood Art Gallery at Hostos Community College, and hagansaintphilip. The Bronx Museum, founded in 1971, was a pioneer and has led the subsequent cultural development, Mr. Serrano said.

“There wouldn’t have been this resurgence of the South Bronx as a place where factory buildings are being turned into loft apartments, where galleries are springing up all over the place –– if places like the Bronx Museum and the Point [a youth and cultural development program in Hunts Point] had not done this when it wasn’t fashionable,” he said.

Ms. Block thinks the enlarged presence of the museum — whose permanent collection focuses on artists of African, Asian, and Latin American descent, as well as those who have lived or worked in the Bronx — will further stimulate the neighborhood. “Having a new building on the Concourse is great for the vibrancy of the community,” she said.

But the road to expansion has not always been easy. The new building’s completion is a triumphant third act in a drama that has lasted more than 15 years. In 1989, the city, under Mayor Koch, allocated $19 million for a construction project that would have quadrupled the size of the museum. Rafael Viñoly was selected as the architect. The funds eventually went elsewhere, although exactly why is a matter of disagreement. The executive director of the museum from 1978 to 1991, Luis Cancel, said in an interview that after Mayor Dinkins took office and made large budget cuts, Bronx Borough President Freddy Ferrer decided “for political reasons … to divert the funds to other capital projects in the Bronx.”

“It was a big blow,” Mr. Cancel said. He left the museum and later became Mayor Dinkins’ commissioner of cultural affairs.

Mr. Ferrer disputed Mr. Cancel’s account, saying in an e-mail message that he allocated the funds in the first place and that he only reallocated them after the Dinkins administration “flatly refused to spend the allocation for the museum.” He added that in his last years as borough president, he allocated capital funds for the museum in conjunction with Mr. Serrrano.

For his part, Mr. Cancel said he was glad the museum persisted and finally managed to expand. “Even though it’s a smaller expansion, it is helping to fulfill the ultimate goal of making a world-class museum on the Grand Concourse,” he said. And he gave credit to Mr. Serrano for lending crucial support: “Without him, this dream would not be being realized.”

For its first decade, the museum was housed in the rotunda of the Bronx County Courthouse. In 1982, it acquired and renovated its current facility, which had been a synagogue. The new building rises beside and is connected to the former synagogue. Under a long-term master plan, the old building eventually will be torn down and replaced with another building designed by Arquitectonica.

One of the architects in charge of the design, Bernardo Fort Brescia, said the new building is intended to give the museum a monumental public image.”The museum [staff] felt that it always lacked a building that made a statement or even made people realize that it was a museum,” he said.

The challenge was creating a visually striking building on a small, midblock lot. The architects exaggerated the building’s verticality with accordion folds, which divide the façade into several tall, thin façades. “It made what was a two-dimensional façade more three-dimensional and more sculptural. It gave it a sense of movement,” Mr. Brescia said.

A steep hill at the back of the building provided an opportunity to create a sculpture garden, which will be the endpoint of the visitor’s ascent through the museum. “In many vertical museums, you climb, and then that’s it, you come down,” Mr. Brescia said. “The sculpture garden is a destination you walk through the museum and discover rather unexpectedly.”

The second floor, including the sculpture garden, will also be rented out for events. “There’s a shortage of beautiful wedding space” in the area, Ms. Block noted with a laugh.

On the third floor, the new building has space for the museum’s education programs, including a student docent program and a teen council, which cultivates young community leaders. The museum also has a residency program, Artist in the Marketplace, which trains artists in career skills and culminates in a four-month exhibition.

Along with the new building, the presence of Ms. Block — who until recently directed Art in General, a contemporary art space in Lower Manhattan — is likely to lure a crowd to the Bronx. The director of I-20 in Chelsea, Paul Judelson, said of Ms. Block, “She single-handedly put Art in General on the map.”

Carol Zakaluk, a co-director of Haven Arts — which is 30 blocks south of the museum in Mott Haven — acknowledges that she’s been to the museum infrequently, but she has high expectations of Ms. Block’s tenure: “If she brings that downtown brazenness and fearlessness, I will make more of an effort to go.”

Ms. Block said her first priority is welcoming the local community, but she also hopes to gain broad attention. “What I need to do is build visibility –– to get people to know about the collection and to organize projects that have impact.”