Barbra Streisand [ tickets ], who last week announced plans for her first national tour in more than a decade, has unveiled an initial batch of dates for the run, and has christened vocal quartet Il Divo [ tickets ] as her opening act.

The outing will get underway Oct. 4 in Philadelphia, and details have been nailed down for shows in 11 cities, including New York, Boston, Detroit, Atlanta, Las Vegas, Los Angeles, Chicago and Washington, DC. The itinerary is shown below.

As previously reported, the tour will comprise a total of 20 shows, according to organizers.

"We believe the experience of working with Barbra Streisand--a truly legendary artist--will forever shape the way we approach our own singing and performing," Il Divo said in a statement. "Her voice and her music have profoundly influenced and inspired so many artists, including Il Divo, and we are thrilled to be sharing the stage with her."

Streisand, who hasn't mounted a national tour since 1994, and in 2000 held what she said would be her last public performance, said last week that she was returning to stage in order to raise funds for various charitable organizations.

"The increasingly urgent need for private citizen support to combat dangerous climate change, along with education and health issues was the prime reason I decided to tour again," she said in a statement. "This will allow me to direct funds and awareness to causes that I care deeply about."

Organizers expect the tour to "provide millions of dollars to organizations concerned with the environment, education and women's health" via the singer's Streisand Foundation, according to a press release.

Streisand hasn't held a public concert since September of 2000, when she performed two-night stands in Los Angeles and New York, ticket prices for which ranged from $150 to $2,500. The shows were billed as her last public performances.

Prior to the 2000 concerts, Streisand played a lucrative New Year's Eve show in Las Vegas on Dec. 31, 1999 that she claimed would "probably" be her final public performance. Ticket prices ranged from $500 to $2,500, and the show set a single-concert box-office record, taking in nearly $14.7 million, according to concert industry magazine Pollstar. Despite the prices, the MGM Grand said that the shows sold out within five hours, and a New Year's Day performance was added.

Over the course of her lengthy career, Streisand has racked up 50 gold, 30 platinum and 13 multi-platinum albums, and is the only artist to have received an Oscar, Tony, Emmy Grammy, Golden Globe, Cable Ace and Peabody Awards, as well as the American Film Institute's Life Achievement Award, according to a press release.

Il Divo is the creation of "American Idol" judge Simon Cowell, who conducted a two-year talent search that yielded four singers from four different countries: America's David Miller, France's Sebastien Izambard, Switzerland's Urs Buhler and Spain's Carlos Marin. The group has sold more than 12 million albums worldwide, according to a press release.