There's no finer way to witness Schleswig-Holstein than from behind the driver's seat of your own rental car. Here are some basic details about Schleswig-Holstein to get your adventure off to the right start. Schleswig-Holstein is a state of Germany. Its capital city, Kiel, is home to approximately 232,800 people. Be sure to chat to some locals and find out more about the cool things to see and do in this terrific destination.