The "Gold Coast" of the Upper East Side is home to some of the neighborhood's most opulent residences, and one of those homes—a 19th-century mansion on East 76th Street—just went on the market for a staggering $50 million. The Wall Street Journal reports that the nine-bedroom home, which was listed by Sotheby's, is being sold by its owner, a Japanese philanthropist. And according to the listing, this house has lots of old-world charm, as well as some interesting quirks. The Parish & Schroeder-designed home was built in 1898 (an addition was made in the 1920s), and its limestone exterior has been well-preserved. There are 20 (!) rooms, including a wine cellar, two staff rooms, two galleries, a rec room, and even a solarium. And even better: According to the WSJ, there are a couple of secret passageways that connect various rooms. One links the library to the card room (yup, there's a card room), and another—hidden beneath a coat closet—leads to the basement. The listing also notes that it's an "ideal home for a serious art collection," noting that a previous owner lined the walls with works by Renoir, Monet, Cezanne, and more. And if you've got $50 million to spend, we're assuming that's not too crazy of a consideration.