In Brussels, Belgium, stands a futuristic structure that looks like a giant cluster of metal spheres. Its name is the Atomium, and its unusual shape is more than just an eye-catching design.

Built for the 1958 World’s Fair (Expo 58), the Atomium was designed to represent an iron crystal magnified 165 billion times. At the time, Belgium wanted to showcase optimism about the future of science, technology, and human progress.

What makes its story even more surprising is that the Atomium was originally intended to be a temporary structure after Expo 58 ended. Instead, it became one of Brussels’ most recognizable landmarks. After a major renovation between 2004 and 2006, the Atomium continues to welcome visitors today.

Expo 58 was also a remarkable success, attracting more than 41.4 million visits during the event.

From a temporary exhibition structure to a national icon—the Atomium proves that something built for a short moment can sometimes end up lasting for generations.