The Space Needle

... was built for the 1962 World's Fair in Seattle. Its top floor is 518 feet (158 metres) above the ground, and the top of its spire is 604 feet (184 metres).

The Space Needle is basically an observation tower; it serves no other purpose than as a viewpoint. There is a revolving restaurant on its top floor, which is said to be the most expensive place to eat in the city.

When completed it was the tallest structure in the USA west of the Mississippi river. According to an answer on quora.com, "In 1962 it was considered a genius artictectural (sic) marvel visited during the World's Fair that year by 2.3 million people from all over the globe."

The Space Needle has featured in several films, including It Happened at the World's Fair (1963, starring Elvis Presley), Sleepless in Seattle (1993) and Austin Powers: the Spy Who Shagged Me (1999).

I'm not sure what first surpassed the Space Needle as "the tallest structure in the USA west of the Mississippi river", but the Bank of America Center in San Francisco had that honour from 1969 until 1972. Today, there are at least six buildings west of the Mississippi that are taller than the Space Needle.

Nor am I sure why it's called the Space Needle, except that the 1960s was the Space Age and anything with "Space" in its name was guaranteed attention.

The Gatlinburg Space Needle was completed in 1969, and is 407 feet (124 m) tall. And incidentally, if the question had mentioned the fact that it was referring to the space needle that was built in 1962 for the World's Fair, there would have been no need to allow Gatlinburg as an alternative answer.