Two central London train stations and nearby roads were reopened on Tuesday after a gas leak prompted the evacuation of almost 1,500 people.
The end of the shutdown followed an emergency services operation overnight to move people out of the area.
The Strand, a major road running from Trafalgar Square to Waterloo Bridge, and surrounding streets were getting back to normal after being closed throughout the morning.
Charing Cross and Waterloo East railway stations, which bring commuters into the capital, were also up and running although trains were expected to be delayed and cancelled.
Train operators were working "to get trains and crew which have been displaced by the diversions back where they need to be ready for people's journeys home this evening," Network Rail said.
Charing Cross Underground station was also reopened, the Transport for London authority said.
"A ruptured gas main was discovered using detection equipment and high levels of natural gas were detected in the atmosphere," a London Fire Brigade spokesman said earlier on Tuesday.
"As a precaution, approximately 1,450 people have been evacuated. They are from a hotel and a nightclub."
Most of those evacuated had been in the 1,000-capacity Heaven nightclub when the alarm was raised about 2:00am.
The club, a landmark on the London nightlife scene for almost 40 years, runs a popular all-night event on Mondays called "Popcorn".
The emergency services operation had continued into Tuesday morning, when an AFP photographer saw staff in some nearby offices later evacuated before authorities announced it was safe to return to work.
"Gas leak fixed, safety checks carried out and roads fully open. Thank you everyone for bearing with us... We're sure London will be fully back to normal soon," the Cadent Gas company said on Twitter.
Westminster Council, which had earlier set up a rest centre, announced residents were "safe to return home".

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