10 Essential 1970s Progressive Rock Albums

Rush's most exhausting effort captured and confounded imaginations everywhere at the time of its 1978 release. The album serves as a neat showcase of the two sides of these prog icons. Of the four tracks, two are high-concept, narrative epics while the other two are fast-paced, no nonsense tunes fit for singles releases.

The LP's opening track, 'Cygnus X-1 Book II: Hemispheres' is a broad, multi-chaptered sequel to the Cygnus song on preceding album 'A Farewell to Kings'. It's 18 minutes of space opera mayhem released at a time where Star Wars was very much the biggest thing since sliced bread.

For listeners knocked over by the opener's ridiculous level of ambition, there's a neat reprieve as more conventional rockers 'Circumstances' and 'The Trees' follow. After a neat and tidy act two, the trio go right back to the old guard with 'La Villa Strangiato', a hectic and maddended multi-parter to close off on.

'Hemispheres' is one of Rush's least accessible, most opaque efforts. It is precisely this reason that has ensured its place in prog rock legend. Taking the imaginative, intellectually challenging concepts and ideals of prog rock to a mind-bending, sometimes existentialist, fantastical extreme, Rush's oddest '70s effort remains one of their most seminal.