Led Zeppelin
Stairway To Heaven

I think "Stairway", a masterpiece of twentieth-century music, deserves a personalized review:

the piece begins (left stereo channel) with a slow harmonic descent from A minor to F that "resolves" and settles back into A minor, arpeggiated by Page on a 6-string acoustic guitar: it's immediately magical, there are some ninth embellishments, and overall the progression is so rich, interesting, and above all evocative that it immediately perks up the ears.
On its repetition, John Paul Jones adds his touch, filling the right channel with a mellotron set on a flute register. A melody with harmonization, a bit approximate in execution but wonderful in melodic line. The atmosphere already created by the guitar enriches, from folk to progressive.
In the center comes Plant's unmistakable tone, which begins to narrate about this lady who's buying a stairway to heaven...the lyrics are his, the meaning isn't very clear but it doesn't matter; the words are refined and unusual, just suitably fitting the spirit of the piece (for now) so ethereal but also solemn. The melodic line followed by the voice is simple, but the harmonic cycle that supports it is so irresistible that one might think a more complex singing would have too much "covered" the sublime chiseling of guitar and flutes...in short, when a song is perfect, it's perfect!
After a couple of verses and an instrumental "round" (over two minutes have passed), the acoustic with a preamble in G restarts in A minor with what is the bridge ("...Makes Me Wonder...") of the "second part," let's call it that, of the piece. The place of the flutes is taken in the right channel by twelve-string electric, played very softly to give a round and rich harmonic timbre. It merely doubles the work of the acoustic on the other channel, but the stereo "mix" of the two guitars, always engaged in an A minor arpeggio but different from the previous one, more epic and romantic, is truly a delight for the ears.
The tempo, meanwhile, is slightly accelerated. At the third verse, Bonzo Bonham enters without knocking, pulling Page's jacket to accelerate further, as well as Jones who begins to fill a bass line playing the tonic notes and little else.
Bonham is simply magnificent: a rock drummer if ever there was one, with an accompaniment seemingly simple but creative and inimitable (drummers who read me know it), a creamy and rolling sound that is a pleasure (in particular the "splatters" supported by his famous bass drum and launched by the snare drum rolls at the end of the verse), infuses the piece with power and penetration.
After four verses, the song calms down for a moment, but then immediately starts again with a fanfare of twelve-string electric (at least two) in unison, of unheard beauty: we are in D, which modulates to C and then to G, it's the most classic harmonic passage one can make on the guitar, good even for beginners and present in hundreds of songs, but here it's sublime! Everything! The sound, the context in the sense of what has been played and sung before...and then the rhythmic division...in short, the piece ascends to the upper floor with shivers down the spine and a proverbial, rhythmically brilliant launch of the third part with Page's solo.
Voted in who knows which recent referendum as "the most beautiful guitar solo in rock," it is harmonically supported by a classic descent A minor, G, F (meanwhile, the "normal," six-string electric guitars have arrived to accompany). It seems Page performed the solo on a Telecaster, which is incredible; the sound is big, full, harmonic, like a Les Paul... The melodic development is beautiful, generous, true sonic nourishment for the ears and brain. Page tugs at our hearts ascending the fretboard to a high D, at the last fret of his guitar. Bonham, meanwhile, accompanies swinging in his way, that is, absolutely powerful and "big".
Bonham's splatter and Plant returns: a beast! An industrial siren! No more folk! His overpowering falsetto, on the same A-G-F base now syncopated, goes head to head with the other beast behind the drums. Bonham hits hard, and when he hits there is no escape: the sonic landscape is devastated by bass drum, cymbals, snare. Page and Jones execute the staccatos leaving the field to the two furies wrestling: only a voice like Plant's can emerge from Bonzo's rhythmic thunder, and then with difficulty Page also makes it through, with dyads on the highs loaded with reverb that bring the piece to the pre-closing stop, followed by a (slightly pleonastic, the only small flaw in these 8 minutes of perfection) tail phrase by Plant alone.

Like all masterpieces, "Stairway" never tires. Von Karajan said that a rearrangement of the piece would be useless: it's perfect as it is. It's the best commentary I've read in these first 35 years of "Stairway".