Slovakia is a country with unexpectedly high density of castles and castle ruins. Hundreds of them are hidden in Carpathian forests, built as a protection against Tatar invasions in 13th century, serving for the next 500 years

http://www.authenticslovakia.com/tours/carpathian-castle-ruins-tour

http://www.slovenskehrady.sk/hrad-dobra-voda

http://www.castles.sk/dobra-voda.php