Pearl Jam's 20th anniversary concerts at Wisconsin's Alpine Valley in 2011 featured guest appearances by Liam Finn, Dhani Harrison, John Doe, Julian Casablancas, Glen Hansard, Josh Homme and members of Mudhoney. But it wasn't until the encores that they unveiled their greatest treat: a Temple of the Dog reunion. 

Pearl Jam and More New Immortals

The Seattle supergroup came together in 1990 to honor the memory of Mother Love Bone frontman Andrew Wood. They recorded a self-titled album in a little over two weeks, right around the time that Pearl Jam came together. Most of the songs were written and sang by Soundgarden frontman Chris Cornell, though he cut "Hunger Strike" as a duet with Eddie Vedder. The album didn't sell much when it first came out, but it became a huge hit when it was rereleased two years later, right as Pearl Jam's commercial popularity was peaking. 

Soundgarden drummer Matt Cameron joined Pearl Jam in 1998, meaning that a Temple of the Dog reunion occurs every time Chris Cornell steps onstage with Pearl Jam. That's happened a number of times over the years, but the 20th anniversary shows featured the longest Temple of the Dog reunion ever at four songs. Here's a fan-shot video of "Hunger Strike" from the second night. 

"Keeping a band together for 20 years is not easy to do," Cornell said from the stage about Pearl Jam. "They have an easy 20 or 30 left in them."