Adobe Creek flows through Redwood Grove, a nature preserve off University Avenue in Los Altos purchased by the city in 1974. In October 2009 Los Altos contracted with Acterra to remove non-native plants and revitalize the redwood, oak woodland, riparian and grassland ecosystems by installing native plants, improving soil conditions, and creating habitat for wildlife such as bird houses and native bee boxes. The coast redwoods (Sequoia sempervirens) were transplanted by the Halsey family from a location on Summit Road in the Santa Cruz Mountains and replaced the native willows. The historic Halsey House, built in the late 1920s by Theodore and Emma Halsey, is a good example of Spanish Revival architecture. The city designated Halsey House a local landmark in 1981 and until recently it housed the Florence Fava collection of Coastanoan or Ohlone Indian artifacts from a nearby archeological excavation in Los Altos Hills (now moved to the Los Altos History House). On June 16, 2010 the Los Altos City Council finalized the purchase of of creekside property from Delbert and Marlene Beumer, who wanted to provide a safe pathway connecting Shoup Park and Redwood Grove.