Editing Auditorium Building (section)

==Design==
Sullivan and Adler designed a tall structure with load-bearing outer walls, and based the exterior appearance partly on the design of [[Henry Hobson Richardson|H.H. Richardson]]'s [[Marshall Field Warehouse]], another Chicago landmark.<ref>{{cite book | title=The Idea of Louis Sullivan | last=Sarkowski | first=John | year=1956 | publisher=Bulfinch Press | page=22 | isbn=0-8212-2667-3}}</ref> The Auditorium is a heavy, impressive structure externally, and was more striking in its day when buildings of its scale were less common.  When completed, it was the tallest building in the city and largest building in the United States.<ref name=FFFE>{{cite web|url=https://www.wsj.com/articles/SB122064771323104933 |title=Form Follows Function, Elegantly: Louis Sullivan designed the Auditorium Theatre's interior to complement its acoustics-driven shape |access-date=September 7, 2008 |date=September 6, 2008 |publisher=[[Dow Jones & Company]] |work=[[The Wall Street Journal]] |author=Henning, Joel |archive-url=https://web.archive.org/web/20080911214215/http://online.wsj.com/article/SB122064771323104933.html |archive-date=September 11, 2008 |url-status=live }}</ref>

One of the most innovative features of the building was its massive raft [[foundation (architecture)|foundation]], designed by Adler in conjunction with engineer Paul Mueller. The soil beneath the Auditorium consists of soft blue [[clay]] to a depth of over 100 feet, which made conventional foundations impossible.  Adler and Mueller designed a floating mat of crisscrossed [[railroad tie]]s, topped with a double layer of steel rails embedded in concrete, the whole assemblage coated with [[pitch (resin)|pitch]].

The resulting raft distributed the weight of the massive outer walls over a large area. However, the weight of the masonry outer walls in relation to the relatively lightweight interior deformed the raft during the course of a century, and today portions of the building have settled as much as 29&nbsp;inches. This deflection is clearly visible in the theater lobby, where the [[mosaic]] floor takes on a distinct slope as it nears the outer walls.  This settlement is not because of poor engineering but the fact the design was changed during construction.  The original plan had the exterior covered in lightweight terra-cotta, but this was changed to stone after the foundations were under construction.  Most of the settlement occurred within a decade after construction, and at one time a plan existed to shorten the interior supports to level the floors but this was never carried out.

In the center of the building was a 4,300 seat [[auditorium]], originally intended primarily for production of [[Grand Opera]].  In keeping with Peck's democratic ideals, the auditorium was designed so that all seats would have good views and acoustics.  The original plans had no [[Box (theatre)|box seats]] and when these were added to the plans they did not receive prime locations.

Housed in the building around the central space were an 1890 addition of 136 offices and a 400-room hotel,<ref name=FFFE/><ref name=ABEOC>{{cite encyclopedia|url=http://www.encyclopedia.chicagohistory.org/pages/89.html|title=Auditorium Building|access-date=September 7, 2008|year=2005|encyclopedia=The Electronic Encyclopedia of Chicago|publisher=[[Chicago Historical Society]]|author=Carey, Heidi Pawlowski}}</ref> whose purpose was to generate much of the revenue to support the opera.  While the Auditorium Building was not intended as a commercial building, Peck wanted it to be self-sufficient.  Revenue from the offices and hotel was meant to allow ticket prices to remain reasonable. In reality, both the hotel and office block became unprofitable within a few years.

<gallery class="center" mode="packed" heights="160px">
File:Auditorium bldg (Interior) HABS.jpg |interior cross-section
File:Auditorium bldg (foundations) HABS.jpg |foundation
File:Auditorium bldg (basement) HABS.jpg |basement
</gallery>