"Who hasn't dreamed of living forever?
If you come to Zalem, you won't know pain, hunger or even death. Zalem is the city of your dreams. To be admitted, all you have to do is fill in a health questionnaire and pay the modest sum of 77,777 dollars.
So what are you waiting for to join us...?"
That's what you read in the many advertisements for Zalem, but in reality the mysterious city of Zalem was a mirage, a gigantic organ trafficking network. The health questionnaire was used to determine the compatibility of future recipients.
Once you were accepted, you were transported to a secret location where you were killed in order to recover your organs.
An AI took your place on the social networks and continued to publish content to make it look like you were still alive.
Zalem was actually three huge towers located in a secret place to store the many servers that AIs need to continue producing elements.
What we do know is that they are still in use and that these towers were covered in photosensitive fibre sheets and sensitive to the kinetic energy of the wind in order to power their energy needs.