"It may sound funny, but we wish to draw the attention of the society towards the importance of cleanliness and hygiene. The aim of the celebration is to create an awareness towards using toilets and sanitation," said Sulabh International Social Service Organisation founder Bindeshwar Pathak.
The cake, which was prepared with the help of local chefs, drew large crowds at the FICCI auditorium here.
"We are celebrating the birthday of late prime minister Indira Gandhi on this day. While celebrating, we are also starting a sanitation revolution in India, which is much needed," added Pathak.
Around 500 children from 15 schools in Delhi along with a large number of liberated manual scavenger women formed a human chain around the replica.
The UN this year declared Nov 19 as World Toilet Day.