Through the last of three tunnels of 25 of them within a 10-mile stretch of track, at the Flatirons rock formations D&RGW’s 3129 East has 25 more miles to reach Denver, 1500-ft. lower in elevation than here. This is the east end of the popular “Tunnel District” where David Moffat’s Chief Engineer Horace Sumner painstakingly blasted that many tunnels — the most in the shortest distance on any railroad.