Libya on Sunday celebrated the start of the revolt that toppled Colonel Muammar Gaddafi, with security forces on high alert.
The uprising began on 15 February, 2011, and ended with Colonel Gaddafi's killing in October.
Now Libya's new rulers are battling critics calling for a 'new revolution' and accusing them of failing to usher in reforms.
Many others are unhappy that the government is yet to disarm militias or write a new constitution.
Fireworks lit up the night sky in cities across the country on Sunday as warplanes and army helicopters criss-crossed the capital.
Thousands of people also converged on squares in Tripoli and the eastern city of Benghazi, waving Libyan flags and playing patriotic songs as long convoys of cars blared music onto the streets.