10 Most Underrated Progressive Rock Albums Of All Time

The Greek outfit's third and final LP was one of prog rock's most ambitious efforts yet at the time of its 1972 release. Built around The Book of Revelation, this apocalyptic epic charts the Christian concept of Armageddon and the rise of the Antichrist among many other heady, often Satanic themes.

Towards the end of this progressive tour de force is a near 20-minute track titled 'All the Seats Were Occupied'. It would hardly be prog without at least one long form piece of work and this montage of sorts of the songs that came before on the LP more than takes the cake. In another showcase of just how diverse the sounds of prog rock can be, the classical Indian melodic structure Raga is employed here to startling and dramatic effect.

The song overall is about as close to an audio acid trip as one is likely to find. The rest of the album is on a similar level with tracks such as 'The Four Horsemen' and 'Aegian Sea' continuing to deliver the ominous, often psychedelic goods. There's also room for some neat instrumental interludes with tracks such as 'The Lamb' and 'The Marching Beast'.

Criminally overlooked in its day, this fascinating, sometimes scary concept effort deserves a great deal more acknowledgment than it's ever received.