The closest is Lotrščak Tower, 1 km north-west of the city centre; the most famous is Trakošćan Castle — #846 of 8,133 worldwide — 50 km north. The oldest dated site in the circle is Tržan Castle in Modruš, founded c. 900.
The 100 km circle reaches into 5 countries — Croatia (24), Slovenia (23), Bosnia and Herzegovina (2), Hungary (1), Austria (1).