MAP OF THE SIDEWALK: December 2010

I caught the MTA Nostalgia Train heading downtown at the West 4th Street station. For the past few years, during the holiday season, the MTA has been running a train composed of old subway cars of models used between the 1930s and 1970s. This year, the Nostalgia Train is running along the F line for several hours each Sunday in December, from Second Avenue to Queens Plaza. Some of the cars are on loan from the New York Transit Museum on Schermerhorn Street in Brooklyn, where they are displayed year-round. Others are kept in storage and sometimes used to train firefighters in dealing with subway fires.

Most of the train was dark green, bolted and boxy in shape. At West 4th I boarded the head car, which on the inside felt like a rolling basement cafe, with red upholstered seats, bare bulb lighting and ceiling fans. A burnt motor smell hung in the air. The lights periodically cut off for a few seconds at a time, which was still common on the subway cars I remember riding in the 1980s.

At Second Avenue the train sat for around 15 minutes. Standing on the platform, I struck up a conversation with a gray-bearded man wearing a puffy down coat, who told me he had helped refurbish some of the cars. He showed me car No. 1575, a conspicuously silver car in the middle of the train. This car, he told me, was an old R7 model that the MTA had turned into a prototype for the R10, which seems to have been a kind of missing link in the evolution of New York City subway cars. It had old-fashioned wicker-looking green and yellow seats, but a bright blue floor with yellow trim that seemed to prefigure the 1970s. The lighting was fluorescent, which the subway refurbisher told me was a first when the R10 cars were built in the years after World War II. The fans were not ceiling fans, but more like upside-down table fans, hanging in pairs from the ceiling. Some cars of this model were apparently still being used in the 80s; I remember riding on a car that looked like one sometime around 1987 or 1988.

The doors between the cars were kept open. During the return trip uptown, I walked through the cars back toward the front. Many of the other passengers had clearly come to see the Nostalgia Train and navigated the straps and poles with cameras and video recorders. But a lot of passengers, particularly at the high-traffic stops at 34th Street and 42nd Street, seemed surprised and got on hesitantly. People looked up at the vintage ads on the walls, hawking Imperial Whiskey, Burma Shave and Rockaways' Playland at 98th Street and Rockaway Beach.

Because it was the last trip of the day, the train's uptown termination point was 47th - 50th Streets, Rockefeller Center. The passengers waited on the platform and applauded as the train disappeared down the tunnel, surprisingly fast and loud.

After the train had gone, I stood talking to a man in a baggy brown jacket who said he had been riding it back and forth all day. He had written down the numbers of the cars on a piece of notebook paper. While we were standing on the platform a modern F train, sleek and silver with red LCD lettering, hissed smoothly into the station on the uptown side. The man I was talking to walked up to the motorman's window in the first car and turned his head to look at the signal board up near the ceiling. He told the motorman the train in the tunnel up ahead was the Nostalgia Train.

"I understand," said the motorman. "But who are you?"

"Train buff," the man said, shrugging.