India, July 3 -- At the Zollverein Coal Mine Industrial Complex, the past isn't tucked away - it looms, all steel and symmetry, as if the machinery just paused for a moment. Standing beneath the headframes, the scale of the place does its own quiet talking. This is one of the former industrial sites in German's Ruhr that's been reworked. Now, these sites are active systems being repaired and reconnected. The International Garden Exhibition 2027 sits against this background.

"I used to work underground, more than 1,000 metres deep," said Hans Jurgen Zielke, who began working here as a miner at 15. "It was very dark, very hot, very dirty." Decades later, now retired, he has returned - not to mine coal, but to interpret the place for visito...