The 1880 Denver & Rio Grande Railroad (D&RG) Antonito Depot is an important and distinctive masonry example of a combination-type depot active in the San Luis Valley. 

The Nelson House is an excellent example of Usonian architecture.  Designed by Boulder architect James M. Hunter, the 1951 house displays many of the defining elements of the architectural type, such as large eave overhangs, integration of indoor and outdoor space, and an emphasis on horizontality, enhanced by the use of the flat roof and ribbon windows.

The academy is associated with the early development of education in Colorado and with the development of Boulder’s University Hill neighborhood. 

Completed in 1892, this pin/rigid connected, eight-panel Thatcher through truss is significant for its unusual structural style, patented in 1884 by Edwin Thatcher, then Chief Engineer of the Keystone Bridge Company.

The McKenzie Well was the site of the 1901 discovery of the Boulder Oil Field, the first discovery of oil in the multi-state Denver Basin.  The field reached its peak production in 1909 with an annual output of 85,000 barrels of oil. 

The Hotel Boulderado was the culmination of the Boulder community’s efforts to fund the construction of a major downtown hotel.

Derived from a Ute word meaning "healing waters", the site is associated with the early exploration and settlement of the area.

Completed in 1891, the school is a good example of an eclectic design, combining Gothic and Romanesque elements as executed by the architectural firm of Varian and Sterner.  

The adobe house, constructed sometime between 1880 and 1903, represents the Hispanic contributions to the settlement and development of Archuleta County. 

Constructed in 1925-1926, the First Baptist Church of Boulder is an excellent example of Late Gothic Revival architecture.