Vignola's Castle or Rocca is said to date back to the 9th century. Built originally for defensive purposes, in the 15th century it was transformed into a opulent home, covered in frescoes and decorations.
These days the castle is used for conventions and exhibitions, which are held in its regal rooms. You can pay a visit to the castle, and organise a guided tour (phone in advance) if you prefer.
Unfortunately the castle was closed when we were in Vignola.