Carlstens Fästning (Carlsten Fortress) – This 17th-century fortress is located high up on the island of Marstrand. It’s one of Sweden’s centuries old fortresses that become tourist attractions. Carlsten Fortress was once a military and prison facility built to safeguard Marstrand, which was an essential free port (trading zone) before. I had the opportunity to learn the history of Carlsten Fortress […]