I couldn't find the battlefield site of Breitenfeld on any map. I suspect it's been pretty much gobbled up by the spread of Leipzig and Halle. But we did find the site of the battle at Lutzen where Gustavus Adolphus was killed in OTL. It's close to Breitenfeld, so the terrain would have been very similar.
There's a monument to Gustavus Adolphus at the site, which I'll show in several pictures. Then I'll post some pictures showing the surrounding countryside. The best way to describe Saxony is... flat. (Except the southern part below Dresden, where it starts climbing into the Erzegebirge mountains which form the boundary between Saxony and Bohemia.)


If I'm translating the German properly, the inscription on the monument reads: "Here fell Gustav Adolf on November 6, 1632."