Hello how may I help you? help me with city facts I can help you with that. What would you like to know? what is the tallest building in Denver in Colorado The tallest building in Denver, CO is the Republis Plaza how tall is that now? The Republis Plaza is 75 stories high, approximately 1100 feet does it have a viewing floor open to the public? It has viewing platforms on the 60th and 70th floors i'll visit it soon. thanks Great, have a nice day