Madonna will crank up her Sticky & Sweet tour again this summer with about 25 more shows in the U.K. and Europe, which will add to the total of what's already the top-grossing tour ever by a female or solo artist.

The final leg of the tour will start in London at the O2 Arena on July 4. Madonna will also play the Manchester (U.K.) Evening News Arena, with the rest of the dates on the tour being stadiums in European markets she has either never played or hasn't played in several years, according to tour producer Arthur Fogel, chairman of global music for Live Nation.

Adding another leg to a tour is a highly unusual move for Madonna. "It absolutely has not happened in the four tours I've been involved with," Fogel tells Billboard.com. "There has been talk [of extending] during each one, but it has never come to be. But with this one, she loves the show, she's had a great time and she's excited about playing new markets."

Fogel says the demand is clearly present in these fresh Madonna markets; London is the only repeat market from the 2008 leg. "It's amazing when you look at the number of markets that she's never played, including this last run in 2008," he says. "We went to quite a few markets she has never played or hasn't been to in 15-plus years. This [extension] is really a continuation of that in the sense of playing new and different markets."

Madonna has enjoyed remarkable box office growth over her past four tours, raking in $75 million in 2001, $125 million in 2004, $194 million in 2006 and $280 million last year, according to Billboard Boxscore. All of these tours were produced by Fogel and his team, and all included roughly the same number of dates (55-60 shows). Attendance has also remained steady, and ticket prices were the same on the past two tours, Fogel says.

The extension will take Sticky & Sweet to around 80 shows, and boost it well into the top five grossing tours of all time. Despite the more than six-month break, the tour will feature the same production and performers as 2008. "It is a long hiatus, but everybody was excited to continue," Fogel says. "So we basically worked out the arrangements for all the performers, crew and equipment and we'll be ready to go."

The Sticky & Sweet tour was the first under a 10-year multi-rights agreement between Madonna and Live Nation, valued in some reports at about $120 million.