It was 40 years ago this week when Led Zeppelin released their sixth studio album – a double that arrived at a point when a brattish new guard would soon come along to wipe away prog rock dinosaurs (albeit only for a while). The album remains, then, a testament to rock's golden age, and there are moments on it that still sound like Thor's mighty hammer whistling a merry tune. Like previous recent Led Zep reissues, this is remastered by the band's guitarist, Jimmy Page, and comes with a range of purchase options . Remove the fan-only gubbins, however, and you're left with a classic rock record from a band at the height of their experimental powers: acoustic miniatures (Bron-Yr-Aur), skittish pop (Down by the Seaside), funk-metal (Trampled Underfoot), and – surely the band's most treasured musical epic – the thundering, shuddering beast that is Kashmir. ledzeppelin.com