It's funny, I was downtown this weekend and had a very similar thought walking through the Union Trust building. Thinking of all the people who passed through that building at one time. And how now people make memories there in different ways. But eventually whether it be because we'll kill each other off, or that we'll figure out how to leave Earth to colonize other worlds, it's likely all this that we've built will sit empty and then eventually reclaimed until there's virtually no trace they were ever there and all.