Meaning of "an dem beschriebenen landestypischen Un-Charme"

Question

From Der Spiegel:

Die Bahnhöfe waren schmutzig, das Westberliner Pflaster war nicht anders als das von mir bislang betretene. Der Berliner Tonfall hinterließ nicht den Eindruck, dass 28 Jahre an dem bereits von Theodor Fontane beschriebenen landestypischen Un-Charme irgendetwas geändert hätten. Ein Leben im zweifellos freieren Teil der Stadt war kein Garant für gute Laune.

What does the text in bold mean? I understand that the rest of the sentence means

The Berlin tone did not leave the impression that 28 years had changed anything.

But what is the "beschriebenen landestypischen Un-Charme"? And why is the preposition "an" used here?

Answer 1

It's a somewhat difficult sentence. The key phrase is daran etwas ändern (change it, make changes to it), in this case an dem Un-Charme (a made-up word to denote the opposite of charm). This only leaves landestypisch (typical of the country, in this case Berlin) and bereits von Theodor Fontane beschrieben (already described by Fontane, a famous author and Berliner who died in 1898.)

To put it all together:

... did not give the impression that 28 years had changed anything in the typically Berlin non-charm already described by Theodor Fontane.