Ramo, who was the wife of aerospace pioneer Simon Ramo -- the "R" in TRW -- died of natural causes at UCLA Medical Center, her family said.
Rob Cutietta, dean of the USC Thornton School of Music, called her "a major philanthropist who would just make it happen."
"She was such a wonderful person. She gave money, and she cared," he said. "She had a lasting impact on the school."
In 1973, groundbreaking began for the Virginia Ramo Hall of Music, made possible by a major gift from the Ramos. Worried that her husband did not have a building named for him, Ramo last year funded the renovation of a space now known as the Simon Ramo Recital Hall, Cutietta said.
Elected to the USC Board of Trustees in 1971, she served as its vice chairman from 1986 to 1991. She also co-chaired a university fundraising campaign from 1976 to 1980 that concluded in USC's centennial year and raised $309 million, a university record at the time.
Steven B. Sample, president of USC, said that "USC wouldn't be where it is" without the Ramos and their intellectual and financial contributions.
"If you asked me to name someone who personified what it means to be a Trojan, to be a part of USC, it would have to be Virginia," he said. "She set a standard."
With her husband, she established in 1971 the Ramo Music Faculty Award, given to a faculty member who has done an outstanding job teaching.
Through the Ramo Foundation that the couple co-founded, she also helped create the Ramo Auditorium at Caltech and endowed chairs, awards and scholarship funds at several other universities.
One of three children, she was born Virginia Smith in 1916 in Yonkers, N.Y. When she was about 5, her family moved to Gardena, where her father owned a dairy.
She played saxophone and worked her way through USC by performing in a women's orchestra.
Through friends, she met Simon, a Caltech student.
In 1937, she graduated with a bachelor's degree in education and married. They soon moved to Schenectady, N.Y., where she taught high school for eight years. During World War II, she also taught business correspondence to military officers.
After the war, the couple returned west so that Simon could work for Hughes Aircraft before co-founding aerospace giant TRW.
She became involved in a nearly endless number of cultural and community activities, which included the Los Angeles Opera and the United Way, and "performed Herculean financial efforts" for most, The Times reported in 1994.
The article also took note of the couple's bond: "Si and Virginia Ramo glitter like diamonds in a close, long marriage with heaps of humor."
In addition to her husband, Ramo is survived by her sons, James and Alan, and four grandchildren.
A celebration of her life will be held in the fall at USC.
Memorial donations may be made to the USC-Keck School of Medicine Virginia Ramo Scholarship Fund, 1975 Zonal Ave., KAM 300, Los Angeles, CA 90089.