The Waldorf penthouse, located atop 1136 Fifth Avenue, is the residence of the Waldorf family. Accessed via a private elevator opening into an enormous great room overlooking Central Park, the penthouse has two floors and at least three private bedrooms. It is worth an estimated $12.1 million in 2014 .
- Unknown (as of 2017)
In Pilot, the Waldorf penthouse is different than it is at any other point in the series. Blair lives there with her mother, Eleanor, and their housekeeper, Dorota. It's mentioned that her father Harold lived there before moving to Paris with his boyfriend, Roman Garrel.
Blair moves into the NYU dorms for a short while, leaving the penthouse to be occupied by Eleanor, Cyrus, and Dorota. In The Treasure of Serena Madre, Eleanor announces she and Cyrus are moving to Paris permanently. After this, Blair moves back into the penthouse. In The Unblairable Lightness of Being, Cyrus purchases an apartment for Dorota, her new husband Vanya, and the new baby they're expecting in Queens. This makes Blair the sole resident of the penthouse, while Dorota still stays there during the day to clean.
Upon returning from Paris in Double Identity, Blair continues to live in the penthouse. In The Undergraduates, Blair invites Serena to move in with her, as Dorota has been hard at work preparing a bedroom for her. Blair and Serena officially become roommates.
Blair and Serena maintain their residence in the penthouse, although Blair briefly considers moving to Monaco permanently once she marries Prince Louis Grimaldi; and Serena considers staying in Los Angeles, where she stayed for the summer, for a job but ends up back in New York. When Serena returns with Ivy Dickens, still posing as Charlie Rhodes, she stays in the penthouse for a short time. In The Return of the Ring, Blair and Serena have a serious fight which leads to Blair kicking Serena out, again leaving Blair the sole resident of the penthouse.
Blair lives in the penthouse alone the entire season, with Dorota still there during the day to work. In Portrait of a Lady Alexander, Dan, having nowhere left to go, asks Blair if he can stay in the apartment for awhile. She agrees, but kicks him out in Monstrous Ball after finding out he wrote an expose article on Chuck. In New York, I Love You XOXO, after the five year time jump, Blair has moved out of the penthouse into a new townhouse with husband Chuck and their son, Henry Bass.