Park Tower, located at 800 North Michigan Avenue in Chicago, is a skyscraper that was completed in 2000. At 844 feet (257 m) tall with 70 floors 67 floors for practical use, it is the eleventh tallest building in Chicago, the 35th tallest building in the United States, and the eighty-third tallest in the World by architectural detail. It is one of the world's tallest buildings to be clad with architectural precast concrete (the Transamerica Pyramid Building in San Francisco is taller). It is one of the tallest non-steel framed structures in the world - it is a cast-in-place concrete framed structure. This building was originally intended to be 650 feet (198 m) tall. But later, the ceiling heights were increased allowing it to reach 844 feet (257 m).
The building occupies a footprint of 28,000 square feet (2,601 m²). Because of the small footprint and the fact that it is a non-steel framed concrete building, this is the first building in the United States to be designed with a tuned mass damper from the outset. While other skyscrapers in America have anti-sway systems, they were always added later. A tuned mass damper counteracts wind effects on the structure. (The 300 ton damper is a massive steel pendulum hung from four cables inside a square cage) Because of its massive weight, the damper has inertia that helps stabilize the building from swaying in the wind.
Designed by Chicago architectural firm Lucien Lagrange Architects, Park Tower is a mixed use tower. As the name suggests, the lower portion holds a Park Hyatt Hotel while the upper levels contain luxury condominiums.