The C&H's office building was sited at the junction of Calumet's two most important roads, near the earliest mine works in the middle of a vast tract of unplatted company-owned land. The building tells of the significance of the preeminent copper producer in the Michigan copper district. Constructed and modified over eighty years of C&H ownership from 1887 to 1968, it reflects the company's growth, decline, and changes in management organization. From here the top administrators directed mining operations. In 1992 it became headquarters for Keweenaw National Historical Park.

The exterior walls are of cut stone rubble trimmed with dark brown brick. The light-colored fieldstone and dark basalt create a mosaic-like pattern. Tall rectangular windows with segmental arches pierce the walls, and slate-clad gabled roofs with bracketed eaves cover the building. The interior held a large private office for the clerk. A staircase hall is in the center section, and in the south end of the building, the superintendent's room and private office. The second floor was intended for the office of the mining engineer, and for sitting and bedrooms for unmarried clerks.