Seats priced at $750, $350, $200 and $100.

The initial round of dates for Barbra Streisand's tour have been announced. The 20-date trek will begin Oct. 4 at Philadelphia's Wachovia Center and will run through the end of November.

Il Divo, the Simon Cowell-constructed classical-pop quartet, has been invited to join Streisand on the road as a special guest. A spokesperson was unable to confirm whether the group will open the shows or be otherwise incorporated into the show.

Tickets go on sale for shows in New York, Boston, Chicago, Philadelphia, Washington, Ft. Lauderdale, Atlanta, San Jose and Los Angeles today (June 12) exclusively to American Express cardholders. Seats are priced at $750, $350, $200 and $100.

As previously reported, the singer has pledged to donate millions of dollars in proceeds to environmental, education and women's health organizations through her own Streisand Foundation. Though her last set of dates was dubbed her farewell tour, the upcoming dates come nearly six years since her last performances at Madison Square Garden in September 2000.

Marty Erlichman, Streisand's longtime manager, says the possibility exists for a DVD, CD or television special from the tour, but those details had not yet been negotiated. "And if Barbra and Ill Divo can find a song that they both like, they’ll record it," Erlichman tells "They’re both on the same label, so that makes life a little simpler."