555 17th Street, Denver

555 17th Street, formerly known as the Anaconda Tower and the Qwest Tower, is a prominent skyscraper located in Denver. Completed in 1978, the building stands at 507 feet (155 meters) and rises 40 floors, making it the seventh-tallest building in Denver and Colorado. At the time of its completion, it was the tallest building in the city, a title it held for three years until it was surpassed by 707 17th Street in 1981.

Originally named Anaconda Tower, the building was the new headquarters for the Anaconda Company, which relocated from New York City to Denver in 1978. In 1997, it became the world headquarters for Qwest, which led to the installation of two large, illuminated Qwest signs on the building. Although Qwest moved its headquarters to 1801 California Street in 2000, the iconic signs remained on 555 17th Street for four more years before being removed in 2004.

Today, 555 17th Street is entirely composed of Class A office space and features amenities such as a tenants' restaurant, a private club, and a conference center. It houses the offices of RSM US LLP, a major accounting firm, and serves as the headquarters for the law firm Holland & Hart LLP, whose name is now displayed on the east side of the building.

The skyscraper is also notable for its environmentally friendly features, including a 600-ton flat plate heat exchanger and electronic ballast lighting technology. These green initiatives have earned 555 17th Street recognition as a "Labeled Building" by Energy Star and the United States Environmental Protection Agency.