Kalmar Castle is a famous Swedish landmark whose history can be traced to as far as 800 years. It was initially built as fortification against pirates and other enemies coming in from the sea. Tagged as “The Key to the Kingdom”, the fortress played avital part in Nordic politics. In 1397, it was the site of the signing of the Union of Kalmar wherein Sweden, Denmark, and Norway were united under one crown. In the 16th century, the fortress was altered into a Renaissance Palace under the direction of the Wasa Kings Erik XIV and Johan III. Today, it stands as one of the best conserved renaissance castles in Europe.