Daniel Ferraris, a retired locksmith from New Jersey, was selling what he called a "firemen's key ring" on eBay, the New York Post reported Sunday.
The set included five keys that controlled of most elevators in the city, power to municipal buildings and skyscrapers, opened subway gates and some firehouse doors and provide access construction sites.
In his eBay ad, Ferraris said all the keys were obsolete and had not been used in years."
Ferraris told the New York Post he collected the keys from various sources.
"I get them from different places. I was a locksmith for many years, and I go to shows and get some from collectors," he said.
The sale prompted concern from the city Department of Transportation, as well New York's police and fire departments.
"These keys are issued to firefighters for emergency situations," said Former FDNY and NYPD Commissioner Howard Safir. "Just anyone having them is very dangerous."