The shell was spotted by a retired army man who was out on an evening walk around 6 PM today.
"The shell could have been lying in the drain for a long time. Since he was an army man, he could identify the object as a cannon ball shell," said a senior police officer.
The army veteran informed police after which the area was cordoned off and the shell was safely removed from there, said the officer.
The National Security Guard (NSG) has been informed about the explosive.
"It is suspected that it was lying in the drain for a long time. Rust has accumulated on it," said the officer.
In January, a mortar shell was recovered from a park in south Delhi's Vasant Kunj area.