Karlstadt lies on the River Main in the district (Landkreis) of Main-Spessart, roughly 25 km north of the city of Würzburg.
From the late 6th to the mid-13th century, the settlement of Karlburg with its monastery and harbor was located on the west bank of the Main.
It grew up around the Karlsburg, a castle perched high over the community, that was destroyed in the German Peasants' War in 1525.
The town was methodically laid out with a nearly rectangular plan to defend Würzburg territory against the Counts of Rieneck.
The former Oberamt of the Princely Electorate (Hochstift) of Würzburg was, after Secularization, in Bavaria's favour, passed in 1805 to Grand Duke Ferdinando III of Tuscany to form the Grand Duchy of Würzburg, and passed with this to the Kingdom of Bavaria.
[3] The town's synagogue was destroyed on Kristallnacht (the Night of Broken Glass, 9 November 1938) by Nazi SA men, SS, and Hitler Youth, as well as other local residents.
(as of 2 March 2008) The town's coat of arms might be described thus: Quarterly, first and fourth azure, second and third argent a fleur-de-lis gules.
[5] Local industry includes Düker Ironworks, the Schwenk Cement Works, and the Kohl Wood Veneer Factory.