The building is composed of Colorado white granite, with large pillars at each entrance supporting a ceramic style roof. Pillars along the west entrance are topped with carved stone statues. Mostly depicting early life in Denver. The tall entrance doors are embedded with copper and glass. Each entrance landing has early 19th century light posts, which also surround the grounds. The gold plated dome commemorates Colorado's Gold Rush days, and the early pioneers and miners who helped build our great state.

Inside the dome towers 180 feet above and contains stained glass dedicated to the 16 initial founders of the city of Denver. The interior of the capitol was built with the rare Colorado Rose Onyx or what is commonly called Beulah Red Marble, named after the city in which it was found. The mauve marble is so rare that its known supply was completely used up in the process of beautifying the capitol. The Cutting, polishing, and installing of the marble took six years, from 1894 to 1900.