Hello how may I help you? What is the tallest building in Denver Colorado? The Republis Plaza. I'd like to know what is the tallest building in New York City? The Empire State Building. What is the longest bridge in California? The Golden Gate Bridge. What is the most populous city in the US? New York City. Which city in the US is closest to Canada? It's a tie between many different places. OK that's all thank you for the facts