There was no immediate claim of responsibility for the threats. But they came after the head of France's counterespionage agency was quoted this weekend as saying that the risk of a terrorist attack on French soil has never been higher.
Bernard Squarcini told Le Journal du Dimanche newspaper that France's history as a colonial master in North Africa, its military presence in Afghanistan and its move to ban burqa-style Muslim veils in public all make the country a prime target for certain radical Islamist groups.
Earlier Tuesday, the ban on face-covering Islamic veils passed its final hurdle in parliament, but there was no indication the threats against tourist sites had any link to the measure.
The proposal has drawn the indignation of the No. 2 of al-Qaida, Ayman al-Zawahri, who said the drive to ban the veil amounted to discrimination against Muslim women. France says its move will uphold women's dignity.
Bomb scares are relatively frequent in Paris, but a threat against such an iconic monument caused more panic than usual.
Following the anonymous threat from a public telephone in Paris, officials evacuated about 2,000 people, and police combed through the 324-meter (1,063-foot) tower, the Paris police spokesman said, speaking on condition his name not be used, in keeping with department policy.
Meanwhile, police blocked off the area under the tower and turned tourists away. Visitors were left milling about nearby, as the tower continued to sparkle and shimmer in its periodic after-dark light show.
Pedro Ferraz, a 24-year-old Brazilian student on a two-week European tour, had planned to go up the tower with his girlfriend on his first night in Paris.
"We were really shocked when we got here, we had no idea about this bomb threat," Ferraz said. "It's really annoying because we planned a lot of our Paris visit around the Eiffel Tower." He was also disappointed, because his travel plans wouldn't allow him to try again the next day.
By midnight - about three hours after the evacuation - the security perimeter was lifted, and people were walking and riding bikes underneath the monument once more. The tower itself, which had 6.6 million visitors last year, usually closes at 11 p.m.
The underground Saint-Michel station, where suburban RER trains converge in the heart of Paris, was also back to normal by midnight after its bomb threat. Officials had evacuated parts of the RER station, and traffic had briefly stopped on one line.
For some, the threat there was particularly chilling.
Algerian Islamic insurgents bombed the Saint-Michel station on July 25, 1995, killing eight people and injuring 150. It was the first attack in a campaign of violence that terrorized Paris subway commuters. Gas cooking canisters loaded with nails, sometimes hidden in garbage cans, were used in many of the bombings.