Malbork Castle

The wall separating the chapel of St. Anny had two small holes, which were associated with a legend.

An excerpt from the article 24 facts about Malbork Castle

It was said that these holes were bricked up. However, every attempt to brick them up, ended with the gaps reappearing the next day and the bricks used for them disappearing. It was said that the spirits of deceased great masters of the Order passed through these holes.