The HRBC Building, which has been christened "Nabanno (New Harvest)" by Banerjee herself, was decked up in flowers of all hues and wrapped in tight security as she formally threw it open amid sounds of bugles and conches.
Security personnel, dog squads, dedicated VIP lanes, fire tenders were put in place for the mega event, which witnessed the presence of top government officials, cabinet ministers and ruling Trinamool Congress lawmakers among other dignitaries.
The chief minister was given a guard of honour on the occasion after she raised the national flag.
The Mamata Banerjee government decided to shift the state secretariat out of the Writers' - from where the British once ruled India - to allow restoration of the heritage complex, which over time has become a "tinderbox" with a disaster waiting to happen.
While the restoration decision has been welcomed, but there are many who have been questioning the whole exercise, especially on the decision to shift the secretariat. Historians and experts too have voiced their concern.
The Banerjee government has appointed a team of experts to carry out the restoration.