“It’s not something you expect,” says Franz Zehetner, who opened a parcel addressed to Vienna’s St Stephen’s Cathedral to discover a skull inside.

The cathedral archivist admits to being taken aback by the package, but alongside the skull was a letter of explanation.

A man in northern Germany said he had stolen the skull as a young tourist about 60 years before and now wanted to hand it back.

He had taken it while on a guided tour of the catacombs beneath St Stephen’s which contain the remains of about 11,000 people buried during the 18th Century.

In his letter, the tourist with the guilty conscience described how he wanted to make peace with himself as he came towards the end of his life.

“After his clarification of the matter, it was touching that someone would wish to make amends for an act of youthful exuberance,” Franz Zehetner told the BBC. “Also that he had carefully preserved the skull over the years – even it was not according to the rules – instead of carelessly getting rid of it.”

It is unclear whose skull the tourist had taken home with him all those years ago, and it has now been re-interred.

Although many of the remains date back to a 40-year period in the 18th Century, members of high-ranking Viennese families were also buried beneath the Cathedral earlier.