Architecture
Who introduced the hourglass profile of the tower?
Space Needle
The architecture of the Space Needle is the result of a compromise between the designs of two men, Edward E. Carlson and John Graham, Jr. The two leading ideas for the World Fair involved businessman Edward Carlson's sketch of a giant balloon tethered to the ground (see the gently sloping base) and architect John Graham's concept of a flying saucer (see the halo that houses the restaurant and observation deck). Victor Steinbrueck introduced the hourglass profile of the tower. The Space Needle was built to withstand wind speeds of 200 mph, double the requirements in the building code of 1962. An earthquake registering 6.8 on the Richter Scale jolted the Needle enough in 2001 for water to slosh out of the toilets in the restrooms. The Space Needle can endure serious structural damage during earthquakes of magnitudes below 9. Also made to withstand Category 5 hurricane-force winds, the Space Needle sways only 1 inch per 10 mph (16 mm per 10 km/h) of wind speed. For decades, the "hovering disk" of the Space Needle was home to two restaurants above the ground: the Space Needle Restaurant, which was originally named Eye of the Needle, and Emerald Suite. These were closed in 2000 to make way for SkyCity, a larger restaurant that features Pacific Northwest cuisine. It rotates 360 degrees in exactly forty-seven minutes. In 1993, the elevators were replaced with new computerized versions. The new elevators descend at a rate of . On December 31, 1999 (New Year's Eve), a powerful beam of light was unveiled for the first time. Called the Legacy Light or Skybeam, it is powered by lamps that total 85 million candela shining skyward from the top of the Space Needle to honor national holidays and special occasions in Seattle. The concept of this beam was derived from the official 1962 World's Fair poster, which depicted such a light source although none was incorporated into the original design. It is somewhat controversial because of the light pollution it creates. Originally planned to be turned on 75 nights per year, it has generally been used fewer than a dozen times per year. It did remain lit for eleven days in a row from September 11, 2001, to September 22, 2001, in response to the September 11, 2001 attacks. The same 1962 World's Fair original poster showed a grand spiral entryway leading to the elevator, but this, too, was omitted from the final building plans. This stairway was added as part of the Pavilion and Spacebase addition/remodel in June 2000. The main stairwell (generally emergency access) has 848 steps in all from the basement to the top of the observation deck. At approximately , the Space Needle was the tallest building west of the Mississippi River at the time it was built by Howard S. Wright Construction Co., but is now dwarfed by other structures along the Seattle skyline, among them the Columbia Center, at . Unlike many other similar structures, such as the CN Tower in Toronto, the Space Needle is not used for broadcasting purposes.