The vocal quartet, which launched the tour's UK leg last night (5/7) in Liverpool, England, will hit at least seven US cities this summer, beginning with an Aug. 9 show in Kettering, OH. The US portion of the schedule is likely to grow in coming weeks as new shows are added to the itinerary.

The full slate of international dates for the group can be found at Backstreet Boys' official website. Currently scheduled US shows are listed below.

"Unbreakable," the group's most recent album, hit stores last fall. The Boys' enlisted an all-star roster of producing talent, including Billy Mann (Sting, Celine Dion) and 'N Sync's JC Chasez, to complete the album, which is the follow-up to 2005's "Never Gone."

"We spent about 14 months on it," the Boys' Brian Littrell told LiveDaily during an interview late last year. "We're happy and proud of the record. It's really the Backstreet Boys of old and where we're headed in the future. We've been at it for quite some time. It's still an honor to be in the fickle music business after 15 years and still making CDs and still having fans who want to hear the music. So we're proud of it."

The album, which peaked at No. 7 on the Billboard 200 chart, marking the group's weakest chart performance to date, is Backstreet Boys' first effort without founding member Kevin Richardson, who departed the group on amicable terms in 2006.

"The first few days without Kevin were a little strange," Littrell told LiveDaily of working without one of the group's original members. "I have to say, not having Kevin there really allowed us to focus on the music and making the best record that we could. We really wanted to make a record for the fans and for ourselves that really didn't miss anybody.

"Vocally, we wanted to have it as strong as it could be and the songs be as strong as they can be. A lot of people know what the Backstreet Boys sound like. It is what it is. We have to continue to sound like that with or without him."