The building was destroyed by air raids during Hezbollah's 2006 war with Israel.
Nasrallah, who was accompanied by the agriculture minister for the ceremony, said in a statement it was important for him to plant the tree at that location.
He urged all Lebanese to follow his example and plant trees outside their homes.
Hezbollah has led a campaign to plant one million trees in Lebanon and Nasrallah's tree was the millionth.
The party is blacklisted as a terrorist organisation by the United States.
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Nasrallah, who was accompanied by the agriculture minister for the ceremony, said in a statement it was important for him to plant the tree at that location.
He urged all Lebanese to follow his example and plant trees outside their homes.
Hezbollah has led a campaign to plant one million trees in Lebanon and Nasrallah's tree was the millionth.
The party is blacklisted as a terrorist organisation by the United States.
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