Backstreet Boys add final summer dates to Sphere Las Vegas residency

Tell me why ... Backstreet Boys keep on tacking on more dates to their Las Vegas residency? Apparently, it's due to "continued fan demand."

The group's added what they say are the "final run" of summer dates for their Into the Millennium show at Sphere Las Vegas. The new shows are set for Aug. 27, 28 and 29. The group's summer run of shows at the venue begins July 16 and was initially set to wrap up Aug. 22.

Tickets for the new shows go on sale March 17 to fan club members at 10 a.m. PT. Those who previously registered for the artist presale when the previous summer shows were announced can buy tickets starting March 18 at 10 a.m. PT. Tickets go on sale to the general public March 20 at 10 a.m. PT at BackstreetBoys.com.

Before the Vegas shows start in July, Backstreet will perform at the BottleRock Napa festival in California. And starting Sept. 25, they'll play a residency in Dusseldorf, Germany, that runs through Oct. 7.