Several sources discuss the Backstreet Boys' highly anticipated residency at the Sphere in Las Vegas, highlighting the overwhelming fan demand that led to additional show dates being added. This residency, titled "Into the Millennium," celebrates the 25th anniversary of their iconic album and marks the Sphere's first foray into mainstream pop acts. The performances will leverage the venue's cutting-edge technology to provide an immersive audiovisual experience for attendees. Information is provided regarding ticket sales timelines, VIP package options, and details about a special anniversary release of the "Millennium" album.