platforms has tempted property owners and developers. Possibly inspired by Terminal City, a development built atop New York's Grand Central Terminal's train shed, Chicago moved to develop the air rights above Union Station's tracks. The first building to be built was that of the Chicago Daily News in 1929. Designed in the Art Deco style, it was the first structure to add a public promenade along the river, which would be named Riverside Plaza. Soon after, in 1932, the new Chicago Main Post Office opened. Also in the Art Deco style, it is a gigantic structure that occupies two full city blocks. The Great Depression and subsequent World War II halted development, but in the 1960s, work began on Gateway Center, a Modernist complex of five buildings. Only the first four were built, and construction lasted into the 1980s through several economic cycles. In 1990 the Morton International Building opened. Now named for Boeing, it is the tallest building yet to be constructed over the tracks. With the construction of River Point beginning in 2013 and 150 North Riverside beginning in 2014, the entire length of the train shed and tracks from Union Station north to Fulton Street and south to Polk Street is enclosed by overhead development. Chicago Union Station's train shed, covered by buildings built above the tracks, helped lead locomotives to funnel significant soot and smoke in and around the station. This was unlike Grand Central Terminal, which has only allowed electric trains into its trainshed since opening. History The current Union Station is the second by that name built in Chicago, and possibly the third rail station to occupy the site. The need for a single, centralized station was an important political topic in 19th and 20th-century Chicago, as various competing railroads had built a series of terminal stations. The numerous stations and associated railyards and tracks surrounded the city's central business district, the Loop, and threatened its expansion. The various stations also made travel difficult for through-travelers, many of whom had to make inconvenient transfers often slowed by street traffic from one station to another through the Loop. Union Station was part of architect Daniel Burnham's city-wide Plan of Chicago in 1909. Predecessors On December 25, 1858, the Pittsburgh, Fort Wayne and Chicago Railroad opened as far as Van Buren Street in Chicago. It built the first station at what would eventually become today's Union