What Are History’s Greatest Utopian Failures?

Exploring the Dark Side of Globalization: Utopian Ideals and Downfall.. I'm diving into the theme of the dark side of globalization and how the relentless pursuit of utopian perfection can lead to societal collapse, much like the tales of the Tower of Babel and the lost city of Aad. Are there any myths, stories, or historical examples you know of where societies, in their quest for perfection or a utopian ideal, ultimately faced downfall or failure? I'd love to hear your thoughts and any stories you might have!