A deed of gift dating from 799, during the reign of Charlemagne, contains the first mention of the "Castle in Linze" and the church of St Martin. Today, the visitor can see the walls of this castle.

In the 17th century, Rudolf II had the castle built, which today is home to the Upper Austrian provincial Museum.
The south wing was destroyed in the City Fire of 1800, and was rebuilt in modern glass-and-steel architecture for the Capital of Culture year 2009. It now constitute the largest universal museum in Austria - the Castle Museum.