Built in 1886, the capitol was constructed mostly of materials indigenous to Colorado, including marble, granite, and rose onyx. Especially inspiring is the gold-leaf dome, a reminder of the state's mining heritage. During normal operation, the dome is open for tours by appointment on the hour and 30 people at a time can go to the top (using a 99-step staircase from the third floor) to take in the 360-degree view of the Rockies; however, as of this writing, the dome is closed as it undergoes extensive repair. Historical tours and a legislative tour are available. Outside, a marker on the 13th step indicates where the elevation is exactly 1 mile high (above sea level). The legislature is generally in session from January through May, and visitors are welcome to sit in third-floor viewing galleries above the House and Senate chambers.