In the center of the square is a tall (circa 50m?) obelisk. This was built by King Ludwig of Bavaria (I think), in memory of 30,000 Bavarian troops who died fighting for Napoleon against the Russians and the Austrians.
Karolinenplatz used to be the heart of Nazi Munich. Braune Haus, the Nazi headquarters, was located just down the street towards KÃ¶nigsplatz, the site of huge Nazi rallies.