2.5 years threat resurrection ^ but what the h#ll:
without any doubt, The Joshua Tree.
Not a very big U2 fan (anymore), but Joshua defined music for me in my youth and as a matter of fact, it's probably my personal favorite album ever made in musical history. Never did and will do an album do things for me like this one did.
As Erik said more then 2 years ago, it's an album for the times brings back nostalgia, it never fails to do that for me.