11.   Police and troops, backed by armored vehicles, have surrounded the square and tried to keep other protesters away.

12.   Checkpoints will be set up on streets surrounding the square, where a ball is dropped annually to ring in the new year.

13.   Customers and staff were trapped in bars and restaurants surrounding the square, as doors and windows were taped up to keep out the tear gas.

14.   Customers and staff were trapped in bars and restaurants surrounding the square, as doors and windows were taped up to protect them from the tear gas.

15.   Hundreds of military police surrounded the square, and hundreds more waited in underground walkways for the flag-raising.

16.   Riot police, wearing helmets and carrying shields, threw tear gas grenades to break up the fighting, which then moved into the slums surrounding the square.

17.   The square was surrounded by police trucks and cars.

18.   The square is surrounded by chic shops, cafes, cinemas and hotels.

19.   While police cars, their sirens wailing, surrounded the square, officers clubbed passers-by and broke up a group of curious onlookers on the steps of the square.

20.   Several flags could be seen hanging from buildings surrounding the square.