The Congress chief also told party workers and leaders at Rajghat that the Mahatma's soul would be pained by what has been happening in India in the last few years.
The initiative was launched by the trust of Sabarmati Ashram, set up by the Mahatma in 1917 on his return from South Africa, in coordination with the Gujarat government three months ago.
The 'Gandhi Sandesh Yatra' on Mahatma Gandhi's 150th birth anniversary began from the Delhi Congress office Rajiv Bhavan at Deendayal Upadhyay Marg and headed to Rajghat.
The Congress president and former prime minister Manmohan Singh were among those who paid floral tributes to the father of the nation.
Ever the man of letters, Gandhi's missives from the time lay bare his passionate belief in non-violence, the core of his philosophy and politics, and also his views on India's Independence.
It was suspected that Gandhi's nationwide campaign against untouchability led to this attack, but the assailant's identity remains unknown to this date.
The party has planned a week-long program that will mark the culmination of the year-long celebrations commemorating Gandhi's memory and it will re-emphasize his values.
According to Shri Bhagwan Sharma, the Delhi chief of the HSS, the institution was established in 1932 at Kingsway Camp here and registered in 1934.
Congress president Sonia Gandhi, former PM Manmohan Singh, BJP veteran L K Advani, Union ministers Piyush Goyal, Hardeep Singh Puri, and BJP working president J P Nadda also paid tribute.
Spearheading the movement against untouchability, Gandhi had halted at Dhumat village on May 30, 1934.
Both the ruling and opposition parties have asked their leaders tor observing October 2 in a grand way with plans for holding padyatras, meetings in villages, and hosting programmes on Bapu.
In a letter to his British disciple Madeleine Slade, who came to be known as Mirabehn, Mahatma Gandhi famously called Champaran the place that introduced him to India.