King Christian IV was the King of Denmark and Norway from 1588 until his death in 1648. He is known for his ambitious building projects, including the construction of the Rosenborg Castle in Copenhagen, which showcased his wealth and power. Christian IV also sought to expand his kingdom through military campaigns, although many of these efforts were met with mixed success. During his reign, Christian IV promoted trade and commerce, establishing the Dutch East India Company and encouraging the growth of cities. His efforts helped to modernize Denmark and Norway, but his later years were marked by economic difficulties and military defeats, particularly in the Thirty Years' War.