The reopening to the public on Sunday was brought forward in response to a video released last week by the Islamic State group showing militants destroying statues in Mosul.
Many of the pieces on display in Baghdad were among the 15,000 looted when mobs ransacked the museum during the plundering spree that gripped the capital when US forces toppled Saddam Hussein in 2003.
The blow was cataclysmic for an archaeological collection until then considered to be one of the world's richest. Close to a fifth of the stolen artefacts have been recovered.
Around 100 visitors trickled into the national museum on Sunday morning -- the start of the work week in Iraq -- as the reopening took Baghdad by surprise.
Like many visitors, education ministry employee Umm Ahmed was a first-timer.
"I always felt I should see the museum," said the middle-aged woman, wearing a black cardigan and a beige headscarf.
"These are masterpieces. I have never felt so proud," she said, slowly walking along a spectacular relief of nine huge slabs depicting Assyrian king Sargon.
"I've been here for an hour and a half, and I plan to visit again. I can't get enough of it," she said, looking in awe at the majestic statues of kings who ruled what is now Iraq several millennia ago.
- Shared history -
Hassan Ali and his two friends rushed to the museum because they wanted to see an artefact representing Ur-Nammu, a Sumerian king who ruled 4,000 years ago and is credited with giving the world its first legal code.
"He's always mentioned in our books and courses, so we had to come and see him," said the law student, who was nine years old the last time the museum was open to the public.
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"We are proud that these civilisations were in our country."
Last week's footage of IS militants in Mosul gleefully smashing ancient statues with sledgehammers and defacing a colossal Assyrian winged bull at an archaeological park with a jackhammer shocked Iraqis and the rest of the world.
Baghdad residents also seemed all the keener to reclaim their museum and rediscover shared history at a time when violence and sectarianism is tearing their religiously and ethnically diverse nation apart.
"It's a place I have dreamt of visiting every night and it is so close to my house," said Aya Mansour, a young writer who made plans to visit the museum with friends on Tuesday.
The museum itself looked like the reopening had taken it by surprise.
Some of the halls were still being refurbished, others were not lit. In one remote hall packed with priceless ancient artefacts, an emergency exit was left open and unattended.
But the museum staff and archaeologists worldwide rejoiced at the fact that Iraqis, for an entrance fee of one dollar, will be able to see their country's greatest heritage treasures without travelling to the Louvre in Paris or to London's British Museum.
"To have it open is extraordinary," said Charles E. Jones, a US professor at Penn State University who has worked on the recovery of artefacts looted in 2003.
"It will make accessible to the Iraqi people and to the world community the unparallelled collections in its galleries, which have been mostly unseen for a generation. It is one of the great national museums of the world," he said.
Standing at the museum's main entrance, Junaid Amer Hameed was beaming.
"Politics has been driving us apart but this here is what can bring us together," the young guide said.