Chants of "Death to America" could be heard outside the former U.S. embassy in Iran on Monday (November 4).
Marking the 40th anniversary of the seizure of the mission - dubbed the "den of spies" after Iran's 1979 Islamic revolution.
Crowds packed the surrounding streets, and state media said marches were being held in some 1,000 communities across the country.
Outside the old embassy, Iran's army chief had harsh words for the U.S. SOUNDBITE (Farsi) COMMANDER OF IRAN ARMY, MAJOR GENERAL SEYYED ABDOL-RAHIM MOUSAVI, SAYING: "They (Americans) will continue their hostilities, like the proverbial poisonous scorpion whose nature it is to sting and cannot be stopped unless it is crushed." Hardline Islamist students stormed the embassy soon after the fall of the U.S.-backed shah.
52 Americans were held hostage there for 444 days, and the two countries have been enemies ever since.
Relations have become increasingly tense between the two powers since U.S. President Donald Trump abandoned a 2015 treaty - under which Iran accepted curbs to its nuclear program in return for lifting sanctions.
The United States has reimposed said sanctions aimed at putting the brakes on Iranian oil exports - in what they says is a bid to force Iran to negotiate to reach a wider deal.
Supreme Leader Ayatollah Ali Khamenei has banned Iranian officials from holding talks - unless the U.S. returns to the nuclear deal and backs down on its sanctions.