King Crimson, just about the most influential and acclaimed prog rock band other than Pink Floyd. Most of their songs fit the crowning moment easily.
"Starless", surely a trope codifier for Epic Rocking. It starts as a subtle and melancholy Power Ballad in 4/4, then it changes into a long, quiet, ominous middle section in a different key and Uncommon Time (13/8, to be precise) with a very minimal guitar part and increasingly edgy drums, then it gets louder and louder until it bursts into crazed sax and guitar solos, still in 13/8 but played much faster, and just when things can't get any more frantic there's a Last Chorus Slow Down which coincides with a return to the home key of G minor and Common Time, and the original Power Ballad melody returns for just one cycle with everyone playing incredibly loudly - and then it ends.
"Pictures of a City", "In The Wake Of Poseidon", "Cirkus", "Fallen Angel", "One More Red Nightmare", and more...
Anything played in In the Court of the Crimson King is made of progressive rock beauty.
"21st Century Schizoid Man" is a real rock 'n' rollercoaster, from the weighty sax and guitar riff that opens the song, to Greg Lake's punchy, distorted rendition of the lyrics, through the epic instrumental interlude led by Robert Fripp on guitar and Ian McDonald on saxophone that separates the last two verses, to the final chaotic, shrieking buildup that cuts off suddenly... and then begins again, getting still louder, only to cut off into silence again. A great track for the band to announce themselves to the listening world.
The solemn "Epitaph" features another parade of instrumental wizardry from each member of the band, especially Robert Fripp on guitar and Ian McDonald on mellotron, as well as a great lead vocal from Greg Lake.
The (almost) title track, "The Court of the Crimson King". There's Greg Lake's soulful rendition of Pete Sinfield's enigmatic lyrics, and the twin tours de force for Ian McDonald that are the energetic mellotron solo and virtuosic flute solo that come between the later verses... and just when the song seems to have ended, the cymbals play on, quietly, until the song appears to begin again, transposed up a whole tone, only to cut off into silence after a few iterations of the opening riff.
The absurdly epic instrumental "Red". Also "Fracture". Or "Providence", which starts off sounding like a horror movie soundtrack before going out into a full blown rocker.
From the Eighties era, there's "Dig Me", with Adrian Belew delivering a delightfully freaky monologue as a car about to be crushed into a cube, capped off with a lovely chorus.
Their 23 minute epic "Lizard" surely qualifies. The whole song is awesome, but the epic, ominous section "The Battle of Glass Tears" stands out.