Originally posted by LikeASong:No, I'm not sure, that's why I wrote an interrogative sentence and not an enunciative one
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Damn hell, you're absolutely rightI always though it was in D all the time, and fuck, it was in Db until the Vertigo Tour!!!! I have doubled checked it with two bootlegs per tour and holy shit, you're so damn right that I can't face my own shame right now
Aha, fear not mate, we all have our lapses - it's tough keeping up with 30+ years of touring, song arrangements, endless amounts of guitars and the like!
Originally posted by Mr_Trek:Is there any other song that's always been performed in the same key? Maybe one of the early songs? 40 maybe?
I'm just taking wild guesses here without listening to the songs.
I think 40's a fair shout, fairly certain that's only ever been in Ab (in full version anyway, not counting snippets, although even then during Elevation it would have been in Ab as a segue out from Bad into Streets) on both album and during tours. Do You Feel Loved, Discotheque, Gone, Mofo, in fact virtually all Pop stuff would probably have retained the same key during tours, although possibly not the same key as on the album - I think Discotheque is Bm on the album but has always been played in Bbm on tours. Same with Mofo, I think it's A/Am on the album and Ab/Abm during PopMart. Gone has always been Eb/Ebm, and I've no idea what key DYFL is in or how it was on PopMart, but on the basis that there were what, 3 performances, it's got a chance of being the same
Beautiful Day, Elevation, Vertigo, always the same key (D/E/E) in both album and live form, and I'm fairly sure that on tour, City of Blinding Lights has always been Ab, although c. the time of the Obama event thing when they played Pride and COBL at the Lincoln Memorial, it was played in A if memory serves, so there's a chance they may have toyed around with that key during the touring during the same time.
(and now I'm going to bed before I spend the rest of the night going through the entire U2 catalogue
) 
Correct me if I'm wrong though. 
like I said at the time, I was just thinking 'out loud' on here, so to speak. NYD? I'm pretty much certain that NYD's never changed, fairly sure it's always been in Ab minor, so actually that would be one example of a song that's always retained the same key both live and on the album, i.e. one that has stayed the same throughout. That said, if anyone's got proof to the contrary, fair dues lol, but I'm pretty much absolutely certain it's never been subject to a key change because it wasn't until the Elevation tour that they started using guitars in standard tuning on stage. Everything was in Eb tuning apart from Edge's alternative tuning for Unforgettable Fire, I'm pretty much confident on that? 