The two-square mile neighborhood, once known as the 'Silk Stocking District', has some of the most expensive real estate in the United States. Until the railroad cut was covered, about 1910, the stylish part of the Upper East Side, with mansions and townhouses lay towards the park, generally speaking, while the area east of Lexington Avenue was a blue-collar district that included stables and breweries. A long high bluff fronting the river north of Beekman Place was dotted with fine suburban villas in the nineteenth century, the last remaining one being Gracie Mansion, home of New York's mayors.
Its north-south avenues are Fifth Avenue, Madison Avenue, Park Avenue, Lexington Avenue, Third, Second and First Avenues, York Avenue, Sutton Place, and East End Avenue.
The area is host to some of the most famous museums in the world. The string of museums along Fifth Avenue has been dubbed "Museum Mile." Among the cultural institutions on the Upper East Side: