The massed ranks of mourners began arriving hours before the 1 p.m. (1100 GMT) funeral of Industry Minister Pierre Gemayel, the sixth critic of Syria to be assassinated in the past two years.
Supporters of the beleaguered pro-Western government had called for the funeral to be turned into a huge show of national defiance and the mourners covered the heart of the capital in red-and-white Lebanese flags.
The angry crowds massed in Martyrs' Square close to the Maronite St George Cathedral voiced their rage at Syrian President Bashar al-Assad and his Lebanese allies -- President Emile Lahoud and militant group Hizbullah.
"Get Bashar's agent out of Baabda," the crowd shouted in reference to the presidential palace.
Lahoud's opponents question his legitimacy after his term of office was extended for three years in 2004 through a controversial Syrian-inspired constitutional amendment.
"We want only the army to bear weapons," the mourners chanted, referring to Hizbullah's persistent refusal to lay down its weapons in accordance with UN Security Council resolutions following the devastating summer war with Israel.
Young men stamped on portraits of Lahoud and his Syrian and Iranian counterparts, Bashar al-Assad and Mahmoud Ahmadinejad.
Gemayel's coffin was being brought down from his home village of Bikfaya in the mountains east of the capital in a cortege that struggled to make progress through the huge crowds.
The coffin had been taken there to lie in state Wednesday as one of Lebanon's leading Christian families received the condolences of well-wishers.
Morning prayers were held in the Gemayels' 19th century residence, before the cortege wound its way out on to the village's main street to the traditional applause from the crowd.
Shots were fired in the air as a mark of respect as the pallbearers made their way slowly through the mass of mourners.
Women threw rice and flower petals at the passing of the coffin, draped in the Lebanese national flag and the banner of Gemayel's Christian Phalange party.
The coffin was placed in a black hearse for the road journey to the capital for the funeral, which was to be attended by foreign dignitaries including French Foreign Minister Philippe Douste-Blazy and Arab League chief Amr Mussa.
Businesses across the country have been asked to remain closed as a mark of respect. The authorities declared three days of official mourning from Wednesday, prompting the cancellation of celebrations for Lebanese independence day.

Copyright AFP (Agence France-Presse), 2006