Stuttgart has a huge railway station project "Stuttgart 21" (I think the 21 refers to the 21st century, not to 2021) that keeps getting delayed. I think the latest date is Dec next year. I don't think it's quite on a par with Brandenburg airport but it's up there.
I don't know much about it except for the fact that it explained why Stuttgart station was such a dump when I was there last time, so I did a bit of reading.
To be fair it looks like it will be pretty good if it does eventually get finished.
We've been dealing with this ballsup for over a decade now: the people of Stuttgart are heartily sick of it: every time I go to catch a train there's a different entrance, usually a long way from the last one. As
@Dogtrousers says, it meant the old station wasn't refurbished, and the new one will probably have less capacity and certainly less recovery space if there's a delay or points failure.
The problem is that Stuttgart is the only German city built in a valley, and the current station covers a fairly large area of very valuable land, and the government of the time thought hey (and possibly some of their rich chums) could make a lot of money selling it off. That government was booted out of office, and we had a referendum, but under the state constitution the referendum had to be held in the whole state, not just one city, and of course people elsewhere thought it was jolly good that there was investment in the rail system, so we're stuck with it.
This of course isn't the main issue: the main issue is that
@Dogtrousers was in Stuttgart and didn't come for a cup of tea. I am mightily offended.