The Lebanon Tunnel was driven into Republican Mountain by the Lebanon Mining company in 1870.

Begun in 1893, the Argo Tunnel extends approximately five miles toward Central City at an average depth of 1,800 feet.

The 1875 two-story false front wood frame building housed the Alpine Hose Company No. 2, one of several volunteer fire companies organized during the late 1800s to protect the community.

The Dodge Ranch, which had its beginnings in 1890, is an important collection of buildings exhibiting the Rustic style of architecture popular in Colorado mountain communities after the beginning of the 20th century. 

Since its completion in 1898, the second floor of this two-story wood frame building has served as the local seat of government and as the social and cultural center for the town. 

The Mill City House represents a method and period of construction as a rare intact one and one-half story Pioneer Log building associated with Colorado's early mining settlements. 

The local community built the school in 1909, and it served the educational needs of the area until 1959.

Replacing a 1902 wood frame building, the circa 1920 Westlake School served as an educational and social facility for rural portions of western Adams County through 1990. 

The 1909 Broomfield Denver & Interurban/Colorado & Southern Railway Depot is architecturally significant as a good example of an early twentieth century combination passenger and freight railroad depot with living quarters for the station agent.

Originally a pile bridge, constructed by the Kansas City Bridge Company in 1900, trusses added by the Pueblo Bridge Company include: a 1902 Pratt through truss, a 1906 Pratt through truss on the south portal, three 1909 long-span Camelback through truss on the north portal, and a 1921 Pratt pony after flooding destroyed the north approach.