The Youth's Quarters

This room, later called the Youths’ Quarters, also had a vaulted ceiling from the late 15th century. It was later demolished and the room converted to Renaissance style when Gustav Vasa considered the castle to be old-fashioned and began renovations in the 1530s. The vault was replaced by a flat wooden roof, and windows were made in the outer walls, allowing people to enjoy the sunlight. An alcove was made in one of the window recesses for a bed.

Gustav Vasa named his second eldest son, John, Duke of Finland in 1556. Turku Castle became the residence of John and his court. The young duke was accompanied by Karin Hansdotter whom John had met at the old Royal Palace in Stockholm. Karin became John's common-law wife and the respected mistress of the castle. Duke John and Karin presumably lived in this room over the period 1556–1558, while waiting for the construction of the ducal living quarters to be completed.

The couple created a court around them, which included Swedish and Finnish nobility, as well as the scholars and craftsmen who had arrived at the castle. While living in the castle, they had four children together: Sofia, Julius, Augustus, and Lucretia. John and Karin moved to new premises when the large halls on the upper floor were completed. Their children kept this room.

Life in the castle was luxurious, and large celebrations often interrupted the monotony of everyday life. However, after about five years spent together in the castle, Karin had to step aside when John began marriage negotiations. For political reasons, the Duke married the Polish princess, Catherine Jagiellon, in 1562. A year earlier, Karin Hansdotter married Klaus Vestgöte, a courtier who was part of John’s inner circle, and moved out of the castle.