The 100-plus protesters and onlookers were mostly peaceful, though there were a few minor clashes around 11 p.m.
His was the third of four monuments coming down in the city's attempt to rectify post-Civil War divisions and eliminate icons of white supremacy from places of prominence, but some object to what they consider erasing history.
Gen. Robert E Lee's monument is next.
Landrieu called for removing the monuments in the emotional aftermath of the 2015 massacre of nine black parishioners at a SC church.
Those removing the first two memorials generally wore bulletproof vests, helmets and face coverings to shield their identities as the work took place well after midnight to minimize attention.
The City Council voted 6-1 in 2015 to remove the monuments after a succession of contentious public meetings where impassioned monument supporters and opponents heckled each other.
The city has been secretive about when and how the monuments will come down, with Liberty Place and Jefferson Davis being taken down at 3 a.m.More news: Australia budget 2017: Treasurer promises fairness and growth
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More recently, lawmakers in the Louisiana House backed a proposal Monday aimed at keeping cities from removing Confederate monuments.
A New Orleans Police mounted patrol circles the statue of Confederate Gen. P.G.T. Beauregard as the statue is prepared for removal from the entrance to City Park in New Orleans, Tuesday, May 16, 2017.
The city plans to have extra security around the Lee statue Friday morning and will block off a one-block radius around Lee Circle to cars before and during the removal in anticipation of protests.
Times-Picayune (http://bit.ly/2rqKQWv ) quotes Blanchard as saying the statue of P.G.T Beauregard had always been a sore spot with him.
The executive director of the Beauvoir Estate in Biloxi, Tom Payne, said it only makes sense for the Jefferson Davis monument to end up there, and the museum would take the rest if the city agrees.
Pierre McGraw, President of the Monumental Task Committee which sought to keep the monuments, called the mayor's actions an "insult" to all who donated money to build them and "honour the memory of their fallen family members". Recent court rulings cleared the way for the monuments to be removed and relocated following heated public debate and legal fights. Dylann Roof, an avowed white supremacist, shot and killed nine black parishioners at the Emanuel African Methodist Episcopal Church. The city said due to "intimidation, threats, and violence, serious safety concerns remain" it wouldn't announce a timeline for Lee's removal.
Of the four monuments, Lee's was easily the most prominent, with the bronze statue alone being close to 20 feet tall.