Governor K.N. Tripathi unfurled the tricolour and took the salute at a colourful march past as West Bengal celebrated the 67th Republic Day on Tuesday.Units from the army, navy and air force took part in the customary parade showcasing sophisticated weapons on the Indira Gandhi Sarani. Kolkata and West Bengal Police personnel, the fire brigade, NCC cadets and school children also took part in the parade which drew huge crowds. Chief Minister Mamata Banerjee, several ministers, bureaucrats and members of the diplomatic corps were present at the programme held under tight security.To mark the day, the Left Front led by the CPI-M formed a human chain in the city, harping on the country's unity and integrity. Led by Left Front chairman Biman Bose and CPI-M state secretary Surjya Kanta Mishra, a host of Marxist leaders and activists joined the chain and urged people to stand up against communal intolerance.The national flag was hoisted at various union and state government offices in the state. A large number of organisations, educational institutions and clubs also celebrated the Republic Day throughout the state by hoisting flags and organising march past by students and children.Flags were also unfurled at the headquarters of political parties in the city.