Boasting the "most expensive suite in America", the opulent Upper East Side accommodation is currently playing host to Meghan Markle and is widely rumoured to be the location of her ultra-private baby shower.
Reports allege the seven-months pregnant Duchess of Sussex and a legion of her most loyal female friends are enjoying a lavish soiree at the Mark's luxurious penthouse - which costs a staggering $105,000 AUD per night.
Meghan, 37, arrived in New York over Valentine's weekend to link up with her closest confidantes ahead of the imminent arrival of Baby Sussex.
The wife of Prince Harry reportedly enjoyed afternoon tea in a private space at SoHo's famed Laduree eatery with best friend and style advisor Jessica Mulroney on Feburary 15.
Duchess Meghan was also pictured leaving the Mark with her former Suits co-star Abigail Spencer on February 19.
The Mark Penthouse is 10,000 square feet and includes five bedrooms, six bathrooms, a 12-seater dining room and a library lounge, as well as a private rooftop terrace with panoramic views of the NYC skyline and Central Park.
With 26 ft ceilings throughout, the Penthouse living room can be transformed into a "full-sized Grand Ballroom" per guests' request.
Designed by renowned French interior artist Jacques Grange, the extravagant two-storey space is described as a "majestic residence representing the pinnacle of modern luxury with exception comfort and care in every detail".
Mirror Online UK reported an army of delivery trucks arrived at the Mark early on Tuesday morning, dropping off an array of gifts which included huge bouquets of pink roses.
A large rectangular package from upscale children's brand Baby Letto was also delivered to the establishment while the Duchess was out enjoying an art museum.
Meghan's girls' trip to New York marks her first time in the city since her May 2018 wedding to Prince Harry.
An inside source told Harpers Bazaar the visit is "a lovely chance to catch up with friends and spend time in a city she loves".
"This will be the last time a lot of [her friends] see Meghan until after the baby is born, so it's nice to share precious moments."
Various conflicting reports have emerged about the attendees of the exclusive baby shower, but guests of honour are said to include Mulroney and Spencer as well as actress Priyanka Chopra and designer Misha Nonoo.
Noticeably absent from the festivities are Meghan's mother Doria Ragland - who was spotted walking her dog in LA early Tuesday morning - and sister-in-law Kate Middleton.