The closest is Piccolomini Castle (Balsorano), 26 km north-east of the city centre; the most famous is Castel Sant'Angelo — #17 of 7,738 worldwide — 79 km north-west. The oldest dated site in the circle is Servian Wall, founded 350 BC.
The 100 km circle reaches into 2 countries — Italy (104), Vatican City (2).















