In February 1922 one or more aircraft flew over the Vatican low enough to disturb the papal conclave then underway. In response, authorities forbade flights over all of Rome until the conclave was concluded.
About seven years later, the Lateran Treaty between the Holy See and the King of Italy included a provision forbidding flights over Vatican City.
Various changes both in technology and in regulation of aviation have happened since that time. Ninety-one years after the aforementioned incident, Pope Benedict XVI announced that he would resign as of the last day of the month, and on February 28 he boarded a helicopter in Vatican City to fly to Castel Gandolfo.
What are the current rules and practices on flights over Vatican City?