Aetna Springs was one of California's famous mineral springs resorts of the late 19th and early 20th centuries. The complex is largely intact, with few alterations subsequent to the last major renovation in the early 1930s, and is one of the finest remaining examples of its type and period in the state. A number of the buildings are architecturally distinguished, and the complex of rustic buildings and associated landscape features are a major statement of the regional First Bay Tradition of the Arts and Crafts design philosophy.

The Aetna Springs Historic District consists of 672 wooded acres containing the former mineral springs resort. The actual developed area is a compact concentration of 32 buildings and a number of associated structures and landscape features at the center of the property; these date from the 1870s to the early 1930s, the period of major development of the resort. Most of the buildings are rustic in character, often incorporating cobblestones, wood shingles, and expressed structure. The major buildings are the original lodge, the dining hall, social hall, and soda fountain building; numerous cottages and service buildings also exist. Several buildings were added or remodeled in the early 1930s, maintaining the earlier rustic character. Integrity remains generally high from this later period: 34 of the 40 property features contribute to the historic character of the district. - NRHP, 2 February 1987