Iran is commemorating Ayatollah Ali Khamenei, the supreme leader 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 his 37-year tenure with a funeral unlike any other in the country’s recent history. The procession will take the ayatollah’s body — which has been preserved since his death on Feb. 28 — to at least five cities across Iran and neighboring Iraq. Tens of millions of people are expected to attend commemorations full of political and religious messaging.

The turnout is being portrayed as a referendum on the legitimacy of Iran’s authoritarian, clerical rule. Ayatollah Khamenei had overseen a brutal crackdown that killed thousands amid nationwide protests in January, deepening societal divisions; the government is likely to use large crowds at the funeral as evidence of enduring broad-based support among Iranians.

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