Čachtice Castle, Slovakia.
The grim appearance of these castle ruins is entirely appropriate, considering it was once the residence - and later the prison - of Countess Elizabeth Báthory, who was alleged to have murdered over 650 people between 1586 and 1610. She would lure young women from the area to the castle with promises of work as maidservants, but once there, the girls were tortured and murdered. Her rank protected her from capital punishment; instead, she was imprisoned within the castle until her death in 1614.
The castle was plundered by Hungarian rebels fighting the Hapsburg Empire in 1708, and has been in decay ever since.