As of 2008, Miami is undergoing a large building boom with 24 skyscrapers that are expected to rise over 400 feet (122 m) currently under construction in the city. Miami's skyline ranks third in the U.S., behind New York City and Chicago, and 18th in the world according to the Almanac of Architecture and Design. The city currently has nine of the ten tallest skyscrapers in the state of Florida, with the tallest being the 789-foot (240 m) Four Seasons Hotel & Tower.
In 2008, Miami was ranked as "America's Cleanest City" according to Forbes Magazine for its year-round good air quality, vast green spaces, clean drinking water, clean streets and city-wide recycling programs. In 2008, Miami was also ranked the 3rd-richest city in the United States and the world's 22nd-richest city in a UBS study.