Led Zeppelin - Led Zeppelin III (1970)

The first Led Zeppelin album I bought also happens to be the one I dig the most. This is where the band's folk leanings and blues underpinnings really come together. And it has their most memorable minor-mode blues ballad — 'Since I've Been Loving You' — which I kept playing till the grooves wore out.

The LP artwork, which has a rotating picture disc, is just fabulous.