An impregnable ground-to-air security apparatus was in place in the capital, specially near Red Fort where prime minister Manmohan Singh unfurled the tri-colour and addressed the nation.
40 CCTVs have been installed in and around the Red Fort to ensure peaceful celebrations while sharpshooters of the NSG have been deployed on the high-rises near the 17th century Mughal monument.
According the sources, Besides the Red Fort, intense vigil were being maintained on key installations like Parliament complex, international airport, railway stations, inter-state bus terminals and Metro stations.
A no-fly zone was put in place around the Red Fort for the nearly 90-minute function.
Delhi Police carried out intensive checks at all the border points.