Message in a bottle
In the 1990s restoration work was being done on a mosque in Turkey that was renowned for its architecture, and for it's architect - the famous Sinan. The building had been commission during the Ottoman Era by a Sultan, as a tribute to his son who had recently died of smallpox at the age of 22.
The crews who were working on the site were professional Turkish conservators and restorers, but when looking at the building they recognised structures that they themselves were unsure how to build. They worried that if they removed some of the worn stones to either repair or replace them, they would not be able to return them in a structurally sound way. In particular, there were intricate stone archways, which the restorers could make neither heads nor tales of.
They decided upon a clever tactic. They would support the arches with a wooden structure, and then remove the stones carefully one by one. Along the way they hoped that they would be able to learn about how the structure of this arch functioned on the inside, like opening up a car to see how the engine functions.
They prepared the arches, and began to remove the stones. However, it turned out that their precautions had not been necessary.
One of the workers noticed something shining inside the stones of the arch. It was a small glass bottle, with a note coiled inside it. The note was written in Ottoman Turkish and so it had to be taken to a linguist to be translated into modern, legible language.
On the note were sophistocated drawings in paper and ink, alongside a message from the architect, Sinan, himself, which read as follows:
"The lifetime of the stones which make up this arch is about 400 years. After 400 years, the stones will be damaged enough that you may wish to replace them. However, you probably won't know how to rebuild the arch after you take out the old stones, because 400 years from now, building techniques will be so different as to be turned on their heads. I am writing you this letter to teach you how to rebuild the arch"
The workers were delighted, and used the information contained on the papers inside the bottle, alongside the intricate plans and drawings to restore the site to its former glory. They learned how Sinan and his team had hauled stones from the distant quarries, shaped them, and fit them together with these ancient Ottoman design techniques - know how that otherwise would have been lost to the ages.