Ambras Castle was built by Archduke Ferdinand II (1529–1595), the second son of Emperor Ferdinand I, for his commoner wife, Philippine Welser, who was not allowed to live in the official residence in the town.
A few notable items make Ambras worth the short trek out of the old town. There's a Habsburg portrait gallery of around 300 works from the 15th to the 19th century. the Spanish Hall with detailed wood ceiling and wall paintings, and an armory.
Somewhat unique is the Chamber of Art and Curiosities, which is found in the same location as it was when first assembled in the 16th century. Here you'll find a mix of oddities collected by Ferdinand II, from coral and goblets to a woodcarving of "Death" by Hans Leinberger, Portraits include Vlad the Impaler and Pedro Gonzalez, who suffered from hirsutism, leaving his full body covered in hair.