 In 2004, the Frost Bank Tower opened in the downtown business district along Congress Avenue.At , it was the tallest building in Austin by a wide margin, and was also the first high rise to be built after September 11, 2001.Several other high-rise downtown projects, most residential or mixed-use, were underway in the downtown area at the time, dramatically changing the appearance of downtown Austin, and placing a new emphasis on downtown living and development.