"A foreigner threw himself from the roof of the Grand Mosque in Mecca" to the courtyard below, "resulting in his instant death", Saudi police told the official SPA news agency.
A French foreign ministry official told AFP in Paris that the dead man was French but gave no further details.
The rare act was not the first of its kind to take place in Mecca, the holiest city in Islam -- which, like other monotheistic religions, prohibits suicide.
The body was transported to hospital, with an investigation underway "to determine the victim's identity, what led to the act and how he was able to commit it despite the existence of a metal fence", SPA said.
Every year, millions of Muslim pilgrims from across the world travel to Mecca and Medina, Islam's second holiest site, also in western Saudi Arabia.
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