In 1875 when Ralston himself died, and the Ralston era of the estate ended. Before his death, Ralston gave the estate to Senator William Sharon, his business partner. Senator William Sharon period, and Radcliffe Hall (1875–1895; 1895–1898) Sharon inherited the mansion in 1875. He did not live in the mansion, but maintained it and used it for entertaining. Ulysses S. Grant visited during this time in 1879, two years after his presidency. In 1885, Sharon died. His family kept the mansion until 1895. After the Sharon family, the mansion was used as a girls finishing school from 1895 to 1898, called Radcliffe Hall. Gardner Sanitarium (1900–1922) From 1900 to 1918, it was then a sanitarium founded and operated by Dr. A. M. Gardner formally of Napa State Hospital, and was called Gardner Sanitarium. After Gardner's death in 1913 the hospital became less popular and finally closed after World War I in 1922. Sisters of Notre Dame de Namur (1922–to present) The sanitarium closed after World War I. Then, in1922, the Sisters of Notre Dame de Namur bought the mansion as a location for their college. The mansion is still owned by the Notre Dame de Namur University today. In 1966, Ralston Hall was designate a National Historic Landmark and in 1972, it became a California registered Historic Landmark. Pending renovation In 2012 an engineering firm advised Notre Dame de Namur University (NDNU) that in spite of the home's relatively good condition “it could not guarantee the safety of the building’s occupants in the event of an earthquake on the San Andreas Fault”. As of April 2012, the building has been closed, pending renovation. Among the required work - which indeed is substantial - is “replacement or retrofit, as necessary, of the entire masonry foundation”, and the "re-roofing, removal and replacement of existing siding and localized replacement of the flooring” of the upper floors. The repairs are estimated to cost at least $12 million. As of February 2019, NDNU has decided to place the Ralston Hall renovation project “on hold” to focus on fundraising for the school. The project has been “placed on an ‘indefinite’ hold”, although it is possible that retrofitting will resume sometime. The structure will be preserved until renovation can begin. Historical Significance In order to help assure its preservation, the City of Belmont commissioned an architectural historian in 2016 to conduct an assessment of the Ralston Hall's