Even the city’s most public places conceal secrets paved over by the years, some more hidden than others. Grand Central Station is no exception despite the 750,000 or so people who make their way through its halls each day. You may already know of the terminal’s secret train track and whispering walls, but did you know that there are tennis courts in Grand Central? Once an exclusive club run by Donald Trump, the courts are now open to the public—and you can reserve a court at midnight.

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