Last week, two real-estate projects in the Chicago tradition of “make no little plans” took some giant steps forward, as both plans won approval from the city’s Plan Commission. One is the ongoing proposal to build a twisting 150-story condo tower-the architect Santiago Calatrava’s Chicago Spire-just north of the Chicago River and west of Lake Shore Drive. Plans for the tower are in their fourth incarnation since the original developer, Christopher Carley, unveiled a rendering of the building in July 2005. (Garrett Kelleher’s Dublin-based Shelbourne Development is now handling the project.) A subsequent redesign made the building look like a stumpy version of the architect’s initial curvaceous beauty, but the latest version brought some sexiness back to the design. On April 19th, the commission gave its unanimous approval to the latest plan; it now goes before the City Council’s zoning committee on April 26th, and from there to the full council in May.

At the same meeting, the Plan Commission also approved a proposal by Walton Street Capital to put offices, condos, hotel rooms, and parking in the mammoth old Main Post Office that hangs over the Congress Expressway just west of the South Branch of the Chicago River. The 2.5-million-square-foot structure, built in 1921 (with a 1933 addition), has stood empty for almost 11 years, since the United States Postal Service moved into a new facility immediately south of it. During those years, proposals surfaced to put everything from an Ikea store to a casino to an auto mall in the architectural white elephant. Walton Street plans to remove almost a third of the building’s gargantuan mass, leaving two end towers and a low section between them that will house the hotel.

The Spire and the post office have different fundamentals. Potentially an instant landmark-and, if built, the tallest building in the Americas-the Spire would put about 1,200 condos along a very desirable stretch of lakefront; the mixed-use, rehabbed post office would drop 300 condos into an area not yet established as a residential neighborhood. Construction on both projects is slated to begin later this year.