Complex sentence: The Palace of Dachau in Bavaria was a medieval castle and became the favourite residence of the Bavarian dukes in the 16th century, it was therefore extended to a massive four wing complex.
Split into simpler sentences: The Palace of Dachau in Bavaria was constructed as a medieval castle and became the favourite residence of the Bavarian dukes in the 16th century. The building was therefore extended to a massive four wing complex.