HOLLY RIDGE, La. – More than three millennia ago, indigenous people built a massive ceremonial mound a few miles from here, an engineering marvel called Poverty Point and one of the oldest known building projects in North America. Today, this is ground zero for what may prove a defining feature of the 21st century’s landscape.

On the eve of a highly-anticipated live X “Spaces” conversation between Elon Musk and former president Donald Trump, the powerful European Union Commissioner Thierry Breton warned in August that authorities would be “monitoring” the conversation for “content that may incite violence, hate, and racism.”