Conversation so far:
What is the Evaluation of Frederick II?
Historians rate Frederick II as a highly significant European monarch of the Middle Ages.
What is one noteworthy accomplishment that Frederick II did while Holy Roman Emperor?
His Sicilian royal court in Palermo, beginning around 1220, saw the first use of a literary form of an Italo-Romance language, Sicilian.

Question: What else did he achieve?
Self-contained rewrite: What else did Frederick II achieve?