The legend, according the Bulgarian Wikipedia page, says that "Satan had a hand in the construction of the bridge. The devil promised the master to share a secret that will make his creation last eternally if he manages to complete it in 40 days. If he failed, however, he would take his soul. Dimitar (the builder) coped with the devil's task and Satan fulfilled his promise, but soon after that, the gifted master died and took the secret knowledge to the grave."

Guilty as charged, the ghost is absolutely planned for, you got me here :)))
I'm glad you've noticed that :)