The Stavros Niarchos Foundation Library, formerly known as the Mid-Manhattan Library, is a branch of the New York Public Library at the southeast corner of 40th Street and Fifth Avenue in Midtown Manhattan, New York City. It is diagonally across from the NYPL's Main Branch and Bryant Park, which are to the northwest. The Library has space for 400,000 volumes across a basement and seven above-ground stories. Its design includes 11,000 square feet of event space and 1,500 seats for library users. The Mid-Manhattan Library opened in 1970 to house the circulating collection formerly located in the NYPL's Main Branch. The branch moved to its current building, a former Arnold Constable & Company department store, in 1981. After a failed attempt to close the Mid-Manhattan Library in the 2010s, the NYPL announced a major renovation of the branch in 2014. Between 2017 and 2020, the branch was closed for renovations funded by the Stavros Niarchos Foundation, and the library was renamed after the foundation.