In 1867, the idea of a subterranean river running beneath Paris captivated residents and sparked debates on its existence. Enthusiasts speculated it was a hidden Roman remnant, prompting amateur explorers and historians to investigate the city's catacombs and tunnels. Despite the lack of significant discoveries confirming such a network, the notion of an aquatic labyrinth added mystery to Paris's urban landscape, reflecting the era's fascination with the unknown beneath one of Europe's iconic cities.