At rush hour at Grand Central Terminal, everybody’s in a hurry.

About 750,000 people pass through Grand Central every day, and while most are running down to catch their trains, a few are heading up to hit some balls.

Four floors above the hustle and bustle, the Vanderbilt Tennis Club sits tucked away.

Dadi Zvulun is the head pro. "Finding a full size tennis court in Manhattan is not easy," he said. "There’s less and less options.”

Let alone a full-sized court with a view looking south over Park Avenue.

“I do sometimes take a peek,” tennis player Heather McCray said. “If I’m not in the point, I look out and I’m like, ‘Oh there’s my apartment down there.’”

Chances are you’ve seen it and don’t even know. The big windows that are so recognizable from the outside give way to the hidden gem inside.

Finding it is half the fun.

Entering from 42nd Street, head into the main terminal, go down the ramp toward the lower level tracks, and across from the Oyster Bar entrance, there are some not-so-obvious elevators. Take those up to the fourth floor, walk down the hall, and there it is.

It took up eight minutes and 34 seconds to find it, and NY1 only got lost once.

“There are so many different entrances and different corridors and so many different sets of elevators, many times people call us and say, ‘I’m on the fourth floor but I have no idea where you are,’ and they realize they’ve taken the fourth floor on a different side of the terminal,” Zvulun said.

When Grand Central Terminal officially opened on Feb. 2, 1913, this space was originally an art studio.

From the 1930s to the 1960s, it was home to the CBS broadcast studios. In the 1960s, it became an athletic club, and in 2011, the new Vanderbilt Tennis Club moved in.

Today it has one full-sized court and two smaller practice courts, where you don’t need a hitting partner — this ball machine can help you work on your game.

Court time is coveted, and not cheap. Hourly rates run from $90 to more than $350. But the court is typically available — and cheapest — if you’re willing to play late from 11 p.m. to 2 a.m.

“We offer what’s called 'Late Night Tennis,' or 'Night Owl Tennis,'" Zvulun said. “After all, this is the city that never sleeps.”

Between four people at a rate of $90 an hour, it shakes out to $22.50 per person.

No matter the time of day, there’s no place quite like it to take a break from the action four floors below and play.

“It’s a moment of freedom in a very dense city,” McCray said.