Edinburgh Castle was originally built as a military fortress in the 12th century before it was later turned into an estate. Like any 900-year-old castle, the structure boasts a slew of dungeons where a number of notorious figures were once held.
Among those who suffered a terrible fate inside its dungeons was Lady Janet Douglas of Glamis, who was accused of witchcraft and burned at the stake; the Duke Alexander Stewart of Albany, who escaped by stabbing his guards and then burning their bodies; and an unidentified piper who managed to venture into one of the castle's many underground passageways only to never be heard from again.
Besides its brutal history of executions, Edinburgh Castle also is near the Real Mary Kings Close (close is a Scottish term for "alleyway"), thought to be haunted since at least the 17th century. The underground site was once home to victims of the Black Plague, who were left for dead there.
Most notably, Edinburgh Castle was the site of one of the largest paranormal experiments in history. The investigation took place in 2001 and involved a team of nine researchers and more than 200 people who dispersed around the famously spooky estate.
All the people involved in the project were told to look out for any signs of supernatural activity without being told beforehand which areas of the castle were considered to be frequently haunted. In the end, 51 percent of participants who were placed in the haunted areas of the castle reported experiencing some sort of paranormal event.
By comparison, only 35 percent of participants said they had experienced similar inexplicable sightings inside the non-haunted areas. These claims included visitors who felt a sudden chill in the air, the feeling of having someone tug on their clothing, and mysterious shadowy figures around the castle. Apparitions of French prisoners and ghost dogs have also been reported.
Some might claim Edinburgh Castle as one of the scariest castles in all of Europe, but it's clear that competition for that honor is incredibly stiff.