BROOKLYN - The FDNY is putting an end to tours through the Atlantic Avenue Tunnel, one of Brooklyn's historic landmarks and the Guinness Book of World Record-recognized world's oldest subway.

The tours take place about 20 feet underground and are led by Bob Diamond, who discovered the tunnel and has been giving tours since the 1980s.

Those who took a tour know that in order to get down to the tunnel, they must go through a manhole, one that the FDNY says is not safe enough.

Concerns about air quality also led to the decision to stop the tours. The FDNY says it is acting in the interest of public safety.

Diamond says he has a permit to take people underground to the tunnel and will continue to operate the tour on schedule.