Historical clue formulations

• Classic rock hit that asks "Is it tomorrow or just the end of time?" — 2020-03-21
• #2 on Rolling Stone's "100 Greatest Guitar Songs of All Time" — 2019-01-11
• What's "all in my brain," in a 1967 rock classic — 2013-05-25
• Song by 56-Across — 2012-11-27