Hello how may I help you? What is the tallest building in Denver CO? The tallest building in Denver, Colorado is the Republis Plaza Is that in the downtown area? Yes, that is correct. Downtown in the business district. What is nearby of interest? There are many museums in the business district that may be of interest to visitors, such as the NMA museum Is it within walking distance? A bus is needed to get to the NMA from the Republis Plaza How far is it? About 5 miles