Walls, towers and gates Porta di Sant' Andrea The Gate of St. Andrew, also known as “The Arch of Frederick II”, was erected in the eleventh century. It was built by the citizens of Ancona as a symbol to show their loyalty to the famous emperor. This is also evidenced by the epigraph on the façade. The style of the current structure is late Renaissance and was conferred on it by the restoration of the 16th century.