A wreath was laid on behalf of Indian President A.P.J. Abdul Kalam at the Shakti Sthal, or Place of Power, a memorial to the late premier, the Press Trust of India reported.
Gandhi's grandson, Parliament member Rahul Gandhi, and other officials including Prime Minister Manmohan Singh offered floral tributes at the grayish-red memorial as religious hymns played in the background.
At the Parliament House, lawmakers paid tribute to India's first female prime minister.
Gandhi, who was assassinated by Sikh extremists Oct. 31, 1984, served as prime minister from 1966 to 1977 and from 1980 to 1984.
She was the daughter of India's first prime minister, Jawaharlal Nehru, and mother of another prime minister, Rajiv Gandh.
In spite of her famous last name, she was of no relation to Mahatma Gandhi.