Some passersby noticed a youth lying in an unconscious state on the road near Kaushambi Metro station, a police official said.
The passersby informed the police, which took the victim to nearby hospital, where doctors declared him dead.
The body is yet to be identified.
"The reason of the death will be known once the postmortem report comes. We have circulated message about the unidentified body to all police stations across the district," the official said.