Answer: Chennai
Notes: Labour Day or International Workers' Day is observed each year on the first day of May to celebrate the achievements of the working class. It is also called as ‘May Day.’ The first May Day celebrations took place in 1890 after proclamation by the first international congress of socialist parties in 1889 in Paris, to dedicate May 1 as the "Workers Day of International Unity and Solidarity." The first May Day celebration in India was organised in Madras (now Chennai) by Labour Kisan Party of Hindustan in 1923. This was the first time the red flag was used in India.
