Iran has begun the commemorations for its supreme leader, Ayatollah Ali Khamenei, who was killed in the first strikes of the U.S.-Israeli war against the Islamic Republic.

Iran’s new leaders are marking his death and 37-year tenure with a funeral unlike any other in recent history. The procession will take the ayatollah’s body — preserved for four months since the bombing — to at least five cities across Iran and neighboring Iraq. Tens of millions are expected to attend commemorations rife with political and religious messaging.

His funeral is being portrayed as a referendum on the legitimacy of Iran’s authoritarian clerical rule — a critical message after Ayatollah Khamenei oversaw a brutal crackdown on nationwide protests in January, killing thousands and deepening societal divisions. Large attendance will be projected as proof it still retains broad-based support.

For Iran’s leaders, the public fanfare is a message to the world, too: After a devastating war that aimed to topple it, the Islamic Republic is still standing.