Today marks the second day of the Apple's iTunes Festival, which brings an entire month's worth of concert to its users. Every night in September, fans can watch their favorite artists perform at the Roundhouse arts center in London without going across the pond, and this year's lineup proves to be one of their biggest ever.

On Day 2 (Sept. 2, 2013), Sigur Ros will take the stage.

The festival kicked off on Sept. 1 with Lady Gaga. Closing the festival is Katy Perry, who announced her involvement on her Twitter feed a little over a week ago.

In between Gaga and Perry, huge music stars like Justin Timberlake, Elton John, The Pixies, Kings of Leon, Queens of the Stone Age and Robin Thicke, will take the stage. 

You can watch on your computer at the iTunes store, Apple TV users can watch in HD from the main page or you can download the iTunes Festival app to your phone or iPad.

Each headlining act is scheduled to perform at 9:00 p.m. London time, which translates to 4/3c.

If you miss it, many acts can be viewed for a limited time after the concert, and of course, iTunes will be selling some of the performances at the iTunes store.

Watch the iTunes Festival Live Stream.