The business district of Chicago around 1905: a grid of blocks packed with steel-framed offices in base, shaft and top, built out to the lot lines and up to the height limit, ringed by the elevated Union Loop, with the lakefront park and the Plan of 1909’s axis along Congress Street.
After the fire of 1871 Chicago rebuilt its business district on the grid surveyed in 1830, squeezed between the river on the north and west, the lake on the east and the railway yards on the south. Land values soared, and the passenger elevator, the steel frame and fireproof terracotta let buildings climb: Jenney’s Home Insurance Building (1885), Burnham & Root’s Rookery and Monadnock, Holabird & Roche’s Marquette. In 1893, alarmed by the twenty-one storeys of the Masonic Temple, the city capped new buildings at 130 feet, and for a decade the Loop grew as a dense, even plateau of ten- to twelve-storey blocks.
Louis Sullivan gave the type its rule in 1896: a tall office building has a base of shops and entrances, a shaft of identical office floors expressed as one, and a top that closes it. The Chicago architects gave it its details: the wide “Chicago window”, the projecting bay, the terracotta skin. From 1897 the Union Loop elevated bound the city’s railways into a ring round the district, and gave it its name.
Burnham’s Plan of Chicago (1909) set this commercial grid in a grand classical frame: the lakefront kept as a public park with museums, and Congress Street widened into an axis leading from the lake to a domed civic centre far to the west. Grant Park, the Art Institute and the Plan’s proposed Field Museum are shown on the lakefront. Click a building to see its rule.