The tallest building in the city is the Astra Tower, which rises 450 feet (137 m) and is set to be completed in 2024. Explore the rise of the Astra Tower, Utah's newest tallest building at 451 feet, reshaping Salt Lake City's skyline.Astra Tower took 4 years from its initial proposal to top out at 450 feet. The final steel beam was placed atop what will be a 451foot highrise in Salt Lake City, making it the tallest building in Utah. The Kennecott smokestack, fourth tallest chimney in the world, is the only operating smelter chimney left in Utah and will turn 35 on Nov. 17.