US Bank Tower, formerly Library Tower and First Interstate Bank World Center, is a 1,018-foot (310 m) skyscraper at 633 West Fifth Street in downtown Los Angeles, California. It is the tallest building in California, the eleventh tallest in the United States, the tallest west of the Mississippi River, and the 65th tallest building in the world. Because local building codes require all high-rise buildings to have a helipad, it was known as the tallest building in the world with a roof-top heliport from its completion in 1989 to 2004 when Taipei 101 opened. It is also the second tallest building in a major active seismic region; its structure was designed to resist an earthquake of 8.3 on the Richter scale. It consists of 73 stories above ground and two parking levels below ground. Construction began in 1987 with completion in 1989. The building was designed by Henry N. Cobb of the architectural firm Pei Cobb Freed & Partners and cost $350 million to build.