In the heart of 1970s Tokyo, a building appeared that looked like it had landed from another planet. A stack of steel capsules, each with a round window like a spaceship, bolted to concrete towers in the middle of a chaotic, booming city.

It was one of the most radical experiments of Japan’s Metabolist movement, a vision of a city that could adapt and evolve like a living organism.

But what happened to that vision? And why, half a century later, does the Nakagin Capsule Tower still fascinate architects, students, and dreamers around the world?