Completely reconfiguring how railways pass through its centre – with tunnels, bridges, replaced foundations and a dramatic new park – the city of Stuttgart is on an ambitious journey to become a transport hub at the heart of Europe.

But it’s now 27 years since that journey began and the promise of economic benefit has clashed hard with the realities of getting the project completed.Like many other countries, Germany is no stranger to massive infrastructure projects that haven’t gone entirely to plan, and the ghost of Berlin’s Brandenburg Airport looms large in the public’s minds.

Complex and controversial in equal measure, this is a look inside Stuttgart 21: one of the world’s most impressive and longest-running railway projects.