Editing Sterling Memorial Library (section)

===Tower===
Fifteen levels of library materials, primarily books, are housed in the building's tower, commonly referred to as the "Stacks".<ref name="SML History" /> Originally intended to house 3.5 million volumes, it is a seven-story structure, with eight [[mezzanine]] levels interleaved between the main stories.<ref name="Snead">{{cite journal |last=Snead |first=William S. |title=The Bookstack Tower |journal=The University Library Gazette |volume=5 |issue=4 |date=April 1931 |pages=77–80 |url=http://digital.library.yale.edu/cdm/ref/collection/rebooks/id/85652 |access-date=4 April 2014}}</ref>  Although encased in a Gothic exterior, the tower's structural system is a welded [[steel frame]], which permits a vertical rise that traditional Gothic techniques would not.<ref name="Husted">{{cite journal |last=Husted |first=Ellery S. |title=The Sterling Memorial Library |journal=The University Library Gazette |volume=5 |issue=4 |date=April 1931 |pages=57–65 |url=http://digital.library.yale.edu/cdm/ref/collection/rebooks/id/85652 |access-date=4 April 2014}}</ref> The [[battlements|crenelated]] roof of the tower is elaborately decorated, complete with a castle-like housing for [[air handler|air handling equipment]].<ref>{{cite journal |title=Castle in the air |journal=Yale Alumni Magazine |date=May–June 2012 |url=https://www.yalealumnimagazine.com/articles/3425 |access-date=6 June 2014}}</ref>

The tower's shelves are estimated to stretch {{convert|80|mi|km}}, contained within {{convert|6.5|mi|km}} of aisles.<ref name="Snead2">{{cite journal |last=Snead |first=William S. |title=The Yale Bookstack |journal=Yale University Library Gazette |volume=3 |date=1928 |pages=21–26}}</ref> In addition to the library collections, the tower houses reading rooms, study carrels, library offices, and special collections, including the [[Yale Babylonian Collection|Babylonian Collection]].<ref name="Snead" /> Access to the Stacks is restricted to affiliates of the university and library patrons.