Karlsburg

Karlsburg (German for "Charles's castle") may refer to:
 * Karlsburg, Mecklenburg-Vorpommern, municipality in Mecklenburg-Vorpommern, Germany
 * Karlsburg Castle in Durlach in Baden-Württemberg, Germany
 * a castle in Karlstadt am Main in Bavaria, Germany
 * a German name of Alba Iulia in Romania