The rugged nature of Boulder Canyon challenged early road and rail engineers. While a stagecoach road was built up the canyon to the town of Nederland, the Colorado and Northwestern Railway opted to go up Four Mile Canyon to reach the mining towns of Gold Hill, Eldora and Ward.

Image/Location	Date	Photographer	Source/Copyright
Boulder Canyon at Castle Rock	1900	Louis Charles McClure	DPL
Boulder Falls	1919	Philip Munz	University of Chicago
Stage Stop Near Boulder Falls	1880	J. B. Sturtevant	DPL
Boulder Hydro Power	1910	Louis Charles McClure	DPL
Boulder Canyon	1898	Louis Charles McClure	DPL
Lover's Leap	1898	Louis Charles McClure	DPL