"The lower half of the Colorado National Bank building was built in 1915 in a neoclassical design featuring marble from the Colorado Yule Marble Company. The upper half of the building was added as an addition in 1926 with a slightly more modern interpretation of the neoclassical base." (from http://www.denverinfill.com/subpages_special_topics/downtown_denver_historic_district.htm)
This is one of my favorite buildings in downtown Denver, but it has been vacant for many, many years. It was recently cleaned and minor repairs completed since it is now a NRHP. The building is currently undergoing renovations http://www.denverpost.com/breakingnews/ci_22313281/renovation-old-colorado-national-bank-building-30-percent . There are two Allen Tupper True murals (http://www.waymarking.com/waymarks/WM8F4R_Allen_Tupper_True_murals_Denver_CO ) inside that I would like to get a photograph of... Oh well.
NPS NRHP link - http://www.nps.gov/history/nr/listings/20100507.htm