I've been listening to the first Boston album a lot recently... if you think about the fact that it came out in 1977, you can understand how it really raised the bar for hard rock music. The amazing thing about the album is that it is in fact a demo... it wasn't recorded in some major label's studio.
You can debate endlessly about what the greatest rock songs of all time are... but I think anyone who really has an appreciation will give a nod to "More Than A Feeling" by Boston. In fact I've come to the opinion that the genre of rock and roll reached it's insurmountable apex when Tom Scholz sang...
When I'm tired and thinking cold...
I hide in my music, forget the day
and dream of a girl I used to know
I closed my eyes and she slipped away
She slipped away. She slipped away.
In fact, after the first time he sings "She slipped away" and adds in the beginniings of the guitar solo... well I can't think of many more poignent moments in rock.
Required listening for anyone who loves rock music.