What is the epic song of a group?

Lady Fantasy - Camel
Gates of Delerium - Yes
Question - The Moody Blues
Karn Evil 9 - ELP
Nine Feet Underground - Caravan
I Walk the Line- Johnny Cash
Ripple - Grateful Dead
Free Bird - Lynyrd Skynyrd. 
Summer of 69 - Brian Adams
Jungleland - Bruce Springsteen
Living on a Prayer - Bon Jovi
Abbey Road Medley - The Beatles
Someone Saved My Life Tonight - Elton John
Italian Restaurant - Billy Joel
Suppers Ready - Genesis
I'd Love to Save the World - Ten Years After
Desolation Row - Bob Dylan

Tomorrow Never Knows or simply Revolver - Beatles
Mellow Yellow- Donovan
Suite Judy Blue Eyes - CSN

No offense to others posting about The Beatles, but for me it's got to be, A Day In The Life.

https://www.youtube.com/watch?v=usNsCeOV4GM

Brownsville Station "Smokin’ in the Boy’s Room"
REO Speedwagon "Ridin’ the Storm Out"
Kansas "Dust in the Wind"
Jackson Browne should be "These Days" but probably "Running on Empty"
Gregg Allman "Midnight Rider"
Thin Lizzy "Johnny the Fox"
Warren Zevon "Warewolves of London"
Foghat "Slow Ride"
Eric Clapton "Layla"
Steely Dan "Reelin’ in the Years"
Doobie Brothers "Jesus is Just Alright"
Neil Young.. simply because of radio play "Southern Man" or "Old Man"
America "Ventura Highway"
Joe Cocker "With a Little Help From my Friends"
Sweet "Ballroom Blitz"
Sniff n’ the Tears "Driver’s Seat"
Walter Egan "Magnet & Steel"
Dire Straits because of MTV "Money for Nothing"
Pink Floyd "Money"
Bob Seger "Night Moves"
Grand Funk  "We're An American Band"

With the Beatles there are a lot of songs to chose from. In my choice of Tomorrow Never Knows placed last  on Revolver though it was the first recorded ushered in a new chapter , I guess the last chapter,  which in my mind made it more epic.