Editing Centennial Exposition (section)

=== Main Exhibition Building ===
[[File:MainBuilding.jpg|thumb|The main exhibition building; at 21½ acres, it was the largest building in world history at the time.]]
[[File:1876FairMainBldgGrandStandW.jpg|thumb|The interior of the main exhibition building looking west from the grandstand]]
The Centennial Commission turned to third-place winner's architect Henry Pettit and engineer [[Wilson Brothers & Company|Joseph M. Wilson]] for design and construction of the Main Exhibition Building. A temporary structure, the Main Building was the largest building in the world by area, enclosing {{cvt|21.5|acre|m2}}.{{sfnp|Beers|1982|p=462}} It measured {{cvt|464|feet|m}} in width and {{cvt|1880|feet|m}} in length.

It was constructed using [[Prefabrication|prefabricated]] parts, with a wood and iron frame resting on a substructure of 672 stone piers. Wrought iron roof trusses were supported by the columns of the superstructure.

The building took eighteen months to complete and cost $1,580,000. The building was surrounded by portals on all four sides. The east entrance of the building was used as an access way for carriages, and the south entrance of the building served as a primary entrance to the building for streetcars. The north side related the building to the Art Gallery and the west side served as a passageway to the Machinery and Agricultural Halls.

In the Main Exhibition Building, columns were placed at a uniform distance of {{cvt|24|feet|m}}. The entire structure consisted of 672 columns, the shortest column {{cvt|23|feet|m}} in length and the longest {{cvt|125|feet|m}} in length. The construction included red and black brick-laid design with stained glass or painted glass decorations. The Interior walls were whitewashed, and woodwork was decorated with shades of green, crimson, blue, and gold. The flooring of the building was made of wooden planks that rested directly on the ground without any air space underneath them.

The orientation of the building was east–west in direction, making it well lit, and glass was used between the frames to let in light. Skylights were set over the central aisles of the structure. The corridors of the building were separated by fountains that were attractive and also provided cooling.

The structure of the building featured a central avenue with a series of parallel sheds that were {{cvt|120|ft|m}} wide, {{cvt|1832|ft|m}} long, and {{cvt|75|ft|m}} high. It was the longest nave ever introduced into an exhibition building up to that time. On both sides of the nave were avenues {{cvt|100|feet|m}} in width and {{cvt|1832|feet|m}} in length. Aisles {{cvt|48|feet|m}} wide were located between the nave and the side avenues, and smaller aisles {{cvt|24|feet|m}} in width were on the outer sides of the building.

The exterior of the building featured four towers, each {{cvt|75|feet|m}} high, at each of the building's corners. These towers had small balconies at different heights that served as observation galleries.

Within the building, exhibits were arranged in a grid, in a dual arrangement of type and national origin. Exhibits from the United States were placed in the center of the building, and foreign exhibits were arranged around the center, based on the nation's distance from the United States. Exhibits inside the Main Exhibition Building dealt with [[mining]], [[metallurgy]], [[manufacturing]], education, and science.<ref>''Philadelphia's 1876 Centennial Exhibition'', pp. 29–30</ref> Offices for foreign commissioners were placed in proximity to the products exhibited along in the aisles along the sides of the building. The walkways leading to the exit doors were ten feet wide.

After the Exposition, the structure was turned into a permanent building for the International Exhibition. During the auction held on December 1, 1876, it was bought for $250,000. It quickly ran into financial difficulties but remained open through 1879 and was finally demolished in 1881.