This is one of our favorites in the list of Top 10 Secrets of Grand Central Terminal. A little known space called the Annex houses the Vanderbilt Tennis Club’s full regulation size tennis court and is accessible to the public (as long as you can get a reservation). Originally installed by a Hungarian immigrant Geza A. Gazdag in the 1960s, it was taken over by Donald Trump in the ’80s, who brought the likes of John McEnroe and the Williams sisters onto its clay courts.
The facility includes a practice court, two practice lanes and a gym. Prices aren’t cheap but you can often find an online deal.