Forbes Mill in Los Gatos: The Surviving Annex Contains Part of an Older Building

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

The stone structure commonly called Forbes Mill is a surviving piece of a larger industrial complex. It is principally the storage annex added in 1880, with part of the earlier flour mill incorporated into one wall.

That distinction makes the building more interesting, rather than less. The remaining masonry records how structures can be enlarged, partly demolished and adapted while retaining physical evidence of more than one period.

The original mill was larger than the building that survives

The National Park Service’s historical account distinguishes the original Santa Rosa Flour Mill, constructed in 1852–1854, from the two-story storage annex added later. It describes stone from Los Gatos Canyon used in the lower stories of the original building, with a timber upper story.

The original building’s height and working program belonged to a flour-production facility. The annex supported that operation through storage, so its survival does not preserve the entire original industrial arrangement.

Reading a historic name as the name of a complex, rather than assuming it always identifies one unchanged building, helps make sense of the site.

The south wall preserves an earlier construction phase

The National Register nomination explains that the annex’s east, west and north walls date to 1880. Its south wall incorporates approximately two stories of the original mill’s north wall, with surviving wall returns functioning as buttresses.

This creates a direct physical connection between the two construction periods. A wall initially built as the outside edge of one structure became part of the later adjoining building.

Demolition can therefore leave more than a freestanding remnant. It can change the role of surviving material within the structure that remains.

Later utility use left another layer of construction

The nomination records a thick concrete partition installed for electrical transformers, along with a new ground-level opening and ducts for transmission lines. These were adaptations for a later power-related use.

The changes show why an old industrial interior may contain elements that do not belong to its first purpose. A heavy partition can be evidence of a later equipment installation rather than part of the original room layout.

The building’s history is thus visible in both its retained masonry and the ways later operators altered the enclosure to support different work.

The mill helped establish a center for settlement

The Park Service connects the mill with the settlement’s early names, Forbes Mill and Forbestown, before Los Gatos became established. The industrial operation created a focal point within the surrounding agricultural landscape.

The town’s historic-district account distinguishes scattered early houses and businesses from later formally laid-out residential subdivisions. It also connects George McMurtry, later a town treasurer, with hauling stone for the annex as a youth.

These links place the building within the formation of a town. Its importance concerns the relationship among work, movement, settlement and the people involved in constructing the place.

Look at the masonry as a record of change

The annex is most informative when its dates are kept separate: the original mill of the 1850s, the storage addition of 1880, and the subsequent adaptations and partial demolition.

That way of looking is useful throughout Los Gatos. A building’s present outline can contain materials and spaces from several earlier arrangements. Understanding which elements belong together produces a more accurate architectural story than assigning one date to everything visible.

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Sources checked October 28, 2026. The nomination describes the building at its preparation date. Older museum references are historical, not current visitor-access information.