Karlsburg Castle in the Durlach district of Karlsruhe characterizes the history of the Baden since 1563. Only the Prinzessinnenbau of the historical building still stands.
Pforzheim was the residence of Margrave Charles II, until he decided in 1563 to move to Durlach. What, if anything, the citizens of Durlach offered him during the negotiations is unknown. Charles decided to extende the medieval Karlsburg Castle into a palace and make it his residence. His successors further extended the castle, until the city was occupied by French troops in 1689.
Wikipedia https://en.wikipedia.org/wiki/Karlsburg_Castle
Coordinates 48°59'54.69" N 8°28'25.874" E