I saw this on imgur last week and everybody was raging calling it the Sears Tower.
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Looks like the same is happening here.
Note that it was never officially renamed the "Sears" Tower, and legally is still documented as the Willis Tower.
People (like me (: ) who grew up hearing and saying Sears Tower will always say it, because it sounds normal to them, whether it is the "official" name or not. It's a fact of life, just like I still say "giff" instead of "jife" when referring to a .gif image. No big deal as long as we know what everyone is talking about.
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Looks like the same is happening here.
Note that it was never officially renamed the "Sears" Tower, and legally is still documented as the Willis Tower.
*mumbles* new Amsterdam should've stuck.