Edward Gibbon tells the whole sad story in his fascinating six-volume book, The Decline and Fall of the Roman Empire. I do recommend it. It’s not for everybody. You probably want to wait until you’re a senior in high school to read it. You need to be a reader who really enjoys reading—it takes a little while to catch on to the rhythm of Gibbon’s writing and the slightly different meanings of some words written two and a half centuries ago. Once you manage that, I promise it’ll be a rewarding experience. It will also be a horrifying experience if you pay attention to what our own idiot political & cultural elites are up to. Having read Gibbon, you’ll view each day’s top news stories with mounting panic and maybe do something drastic like start writing a history blog.
Decline and Fall is available in an abridged (shortened) version, which is the one I read: https://www.penguinrandomhouse.com/books/59496/the-decline-and-fall-of-the-roman-empire-by-edward-gibbon/
and in audio: https://www.audiobooks.com/audiobook/decline-and-fall-of-the-roman-empire-vol-i/244636 It costs 40 bucks so check with your librarian to see if you can borrow it. Librarians are helpful people and can save you a buttload of cash.
A thoughtful entry by a Wiki editor—worth the read: https://en.wikipedia.org/wiki/The_History_of_the_Decline_and_Fall_of_the_Roman_Empire
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