The U-shaped custom house is a five-story Italian Renaissance Revival palace cloaked in Colorado Yule marble carved with classical symbols of the federal government's majesty. Colorado's U.S. Senator Lawrence C. Phipps, Colorado Governor Edwin C. Johnson, and Denver Mayor Benjamin F. Stapleton all lobbied heavily for this building, persuading the federal government to substitute snowy white Colorado marble for Indiana limestone despite a $200,000 price increase. Marble was used lavishly inside and out in a building that helped confirm Denver's role as the hub of Rocky Mountain commerce and as a “little Washington” for federal offices.