Like an in-unit washer-dryer, there are few things in New York City as coveted as a key to Gramercy Park. Manhattan's sole private park—there's only one other one in the city, Queens's Sunnyside Gardens—the block of greenery between 20th and 21st Streets in the Gramercy Park Historic District is only accessible to those who have a key, except for one day each year: Christmas Eve, when the park opens its gates to the public for one hour of caroling fun.
With fewer than 400 keys in existence, each tied to one of the original lots surrounding the park, it's nearly impossible for most mere mortals to enter the park the other 364 days of the year, unless they're a resident of one of the key-holding buildings on the park's perimeter or a guest of the glamorous Gramercy Park Hotel, the Players Club or the National Arts Club.
The public Christmas Eve carols are a tradition dating back to the mid-19th century; today it's run by the Trustees of Gramercy Park, with the nearby Parish of Calvary-St. George's leading the music.
Head to the park on Christmas Eve to sing "Silent Night" from 6–7pm under the glow of the park's Christmas tree.