The protestors, who converged on the city centre from various localities of the city and neighbouring Howrah, was squatting before the Kolkata Municipal Corporation headquarters, shouting slogans and singing songs of freedom.
The participants included students, teachers and other professionals, besides housewives and senior citizens, who gathered at the spot since late in the afternoon.
"The fascist Narendra Modi government is trying to deflect attention from the abysmal condition of the economy by dividing the people on religious lines," said Afroz, who resides in the Taltala area.
A student Ruksana Hamid was livid with the central government for not paying heed to the countrywide protests against CAA.
"I was shocked to hear Home Minister Amit Shah say notwithstanding the protests, the CAA will not be withdrawn at any cost. How can they be so insensitive to the voice of the people?," she asked.
Convener of a joint forum Ratan Basu Mazumdar said the mass demonstration would continue till Wednesday, referring to the Supreme Court hearing petitions challenging the CAA.
"We will follow the court proceedings from here and chalk out our strategy depending on what the court says," Mazumdar declared.
The CAA, passed in Parliament last month, seeks to provide Indian nationality to Hindus, Christ, Sikhs, Parsis, Jains and Buddhists fleeing persecution in Pakistan, Afghanistan and Bangladesh before December 31, 2014.
As per the Act, such communities will not be treated as illegal immigrants now and will be given Indian citizenship.
( With inputs from IANS )