Visitors were evacuated from Paris's Eiffel Tower last night after an anonymous phone call announcing an attack.
About 1,400 people were removed and a security perimeter was set up around the monument. Security guards were also ordered to leave, a decision described as unusual.
Police then searched the area with sniffer dogs for possible explosives.
Security has recently been stepped up across France amid concerns about threats to France over its military campaign in Mali.
The call came from the Paris suburbs and threatened an attack at 9:30 pm (2030 GMT). The anti-terrorism unit is investigating.
Bomb alerts targeting monuments and public places happen frequently in the French capital, but all alerts are "treated very seriously," a police source told AFP.