Dracula’s Prison in Tokat ...

Clues about 'Dracula’s captivity' unearthed in Tokat - ARCHAEOLOGY:
Restoration works in the Tokat Castle have discovered a secret tunnel leading to the Pervane Bath and a military shelter. Two dungeons have also been discovered in the castle, where Wallachian Prince Vlad III the Impaler, who was also known as Dracula, is said to have been held captive in the early 15th century.
 There's a more recent story about it here: Archaeologists Found The Dungeon Where Vlad Dracula Was Imprisoned