According to a popular conspiracy theory, which German city does not exist?

I only know its small airfield. But I went there and confirm that it exists and is a charming place.

There is also "Finland, Australia does not exist" conspiracy theory and also "US states of Wyoming and Idaho does not exist" conspiracy theory and other regions/provinces worldwide according to Wikipedia So weird and strange

Peter Montgomery, if it existed, it would be an interesting place... :)

interesting. sounds like it started bit like game of Chinese whispers .. something misheard which gets repeated and more misheard and misunderstanding from original. it sounds an interesting place though