Hello how may I help you? Can you tell me what the tallest building in Denver, CO is> Certainly. The tallest building in Denver is Republis Plaza Okay and how tall is it? Republis Plaza is 714 ft tall Wow. And when was it built? Republis Plaza building was completed in 1984. Okay. How many floors does it have? 56 stories tall. Hope this helps. Thanks for the info. Anytime! Take care for now