Maybe it was taking the Broadway IRT subway line to East Flatbush that inspired Brooklyn-born Jerry Greene to spend five decades amassing the world’s greatest — and best-kept secret — collection of antique toy train stations.

Now the 67-year-old record mogul is hoping to ride the gravy train for $50 million or more in a private sale of his toys when bids are due at Sotheby’s on Feb 28.

The enormity of the collection is mind-boggling. Only 20 percent of the 35,000 objects Greene has on display in his 5,400-foot basement in Pennsylvania are for sale.

Not even the world’s antique-toy experts knew of Greene’s treasure trove.

“I had nothing to compare it with. I never thought it was really special,” said Greene, a former New York City record promoter who produced the doo-wop hit “There’s a Moon Out Tonight” by the Capris.

Most of the train-station replicas are from 1850 to 1940.

There are also trains and tracks, miniature villages, Ferris wheels and carousels.