The Brown Palace opened in 1892. Frank Edbrooke designed it in a triangle shape, and it was named for its owner, Henry C. Brown. When it was finished, it was the tallest building in Denver.
Wikipedia says an iron and steel frame covered in cement and sandstone made it one of America's first fireproof buildings. It is also one of the first atrium-style hotels ever built.
Theodore Roosevelt became the first sitting president to visit the hotel, on May 8, 1905. In 1959, Lamar Hunt and Bob Howsam met in the lobby to talk about a new football league, and Howsam agreed to own what became the Denver Broncos.