The innovative folks behind the San Lorenzo Valley Museum have been hosting online exhibits since 2012.
With an emphasis on the people and history of the Santa Cruz Mountains, online exhibits have covered topics as diverse as the patents for gadgets and gizmos originating from the area to a celebration of 100 years of women's sufferage.
Check it out here: http://www.slvmuseum.com/index.html
The Santa Cruz Public Library maintains an impressive collection of historical information, including articles about local history, a local news index, articles and photographs of historic local buildings and much more.
Check it out here: https://history.santacruzpl.org/omeka/
The archives of the Museum of Art and History are a treasure trove of windows to the past.
The MAH maintains online guides to its physical archives and collections to help researchers get started.
Check it out here: https://archives.santacruzmah.org/
The folks at the Museum of Art and History know that telling the story of the people, histories and perspectives of the people of Santa Cruz County is a job for the story tellers.
Download and enjoy these stories here: https://soundcloud.com/santacruzmah
As might be expected in a city as old as Santa Cruz, there are a large number of examples of architectural vernacular (including a trolly house!) within the city limits.
The City of Santa Cruz maintains various online resources cataloging designated historic structures, criteria for the historic designation process and downloadable walking tours for history and architecture buffs.
Watsonville is home to a number of historically significant building, including several homes and commercial building designed by famed Victorian Era architect, William Weeks.
You can download a PDF of a walking tour of the all American downtown here: https://www.cityofwatsonville.org/408/Historic-Architecture
The fine folks at the Capitola Museum have produced a downloadable brochure and companion book to provide a reference to 150 years of Capitola history.
Check it out here: https://www.cityofcapitola.org/capitola-museum
The folks at the San Lorenzo Valley Post publish regular articles about the history of the Santa Cruz Mountains.
Check it out here: https://slvpost.com/category/history/