In the Subway Tunnels, Two Contrasting Paths Into New York History Bryan Thomas for The New York Times The Bergen Street "ghost station," which has been closed for decades, is visible only when the Manhattan-bound F train is running express. One is a century-old transit hub permitted to age gracefully beneath Lower Manhattan, its chandeliers, terra-cotta tiles and ceiling of Guastavino vaults perfectly preserved. The Old City Hall Station, which closed in the 1940s, is visible when the downtown No. 6 train turns around after its last stop at Brooklyn Bridge-City Hall. The other is the subway system's forgotten shame, cast in blue spray paint and corrugated metal, then suspended in disrepair since the grime-and-graffiti era of the 1970s, when it served a neighborhood in Brooklyn that bears little resemblance to today's. There are more than a few stations hidden in the city's underground thickets, but none offer more contrasting images of New York's past than these two - Old City Hall Station, the flagship of the Interborough Rapid Transit Company, and the lower level at Bergen Street, last seen widely as the backdrop of a horror film. Now, for equally opposite reasons involving train turnarounds and the vicissitudes of repair, both can be glimpsed for those who know where to look. The first case is deliberate: The Metropolitan Transportation Authority has in recent years begun allowing riders to stay on the No. 6 train as it turns around at the southern end of its run. The second is not. In the last several months, planned and unplanned work on the Culver Line in Brooklyn has often rerouted F trains to the old express tracks that pass below Cobble Hill. Among history-minded riders, the stations have for decades stood as emblems of the transit system's dueling legacies. They are the impossible standard and the indelible blight - the reason that today's wistful older riders can be sorted into two camps: those for whom hindsight has softened the edges of the subway's darkest days, and the dwindling few with memories long enough to include its most regal beginnings. The stations are particularly striking because they can be glimpsed almost accidentally, by a straggler who overslept on the Lexington Avenue Line, waking to discover a turn-of-the-century gem on the loop track at Brooklyn Bridge-City Hall, or by a commuter aboard a surprise express to Manhattan. For such F train riders, there is the dash past the outdoor stations at Fourth Avenue and Smith-Ninth Street, then the telltale dip at Carroll Street, as the platform recedes overhead. And then it appears, faintly at first, followed by two surges of light: the moldering columns, a staircase leading to a dim concourse, and walls of graffiti - some fresh, some apparently decades old. The station was closed to passengers in 1976. "It's sort of a window back into that time when the subway system was different, and not nearly as safe," said Benjamin Kabak, the publisher of the website Second Ave. Sagas, who recently passed the old station during a spell of weekend work on the F. "It looked like the train could stop and let people on right now." But there are few chapters from the system's past that so rankle the transportation authority, which declined to discuss the station in detail. For one, the authority is mindful of persistent calls to restore F express service, fearing that any mention of the station might convince riders that it could be renovated adequately with due care. Officials also noted security concerns and a desire to "discourage urban explorers" from venturing underground. At City Hall, though, a sense of adventure is celebrated. On the authority's website, members of the New York Transit Museum are encouraged to purchase $40 tickets for a tour of the station, referred to by its nickname, "The Jewel in the Crown." There are two sessions in December. For the 100th anniversary of the subway system in 2004, the station, which was closed in 1945 because its platforms could not support 10-car trains, was reopened for a ceremony with Mayor Michael R. Bloomberg. Workers dressed in turn-of-the-century outfits, as Mr. Bloomberg helped maneuver a vintage four-car train. He mused that few things had changed since the system's inception, invoking a song for which Leonard Bernstein wrote the music to reinforce the point: "The Bronx is still up, and the Battery is still down, and we still ride in a hole in the ground." Less elaborate outings have also been condoned. Though conductors were in the past known to expel passengers at the end of the No. 6 line, announcements on many trains have been adjusted to reflect a change: "The next stop on this train will be Brooklyn Bridge-City Hall, on the uptown platform," the message now says, in a nod to riders who might remain on board. The cost for them, of course, is a single ride.