Her virginity, we mean.
Short of discovering a long-lost diary (and from all known accounts, she didn't keep one), we may never be entirely sure where Carole Lombard learned the ways of sex. But there's one site that's a leading candidate -- a building on 7000 Romaine Street in Los Angeles:
This was Howard Hughes' headquarters in 1929, and Lombard biographer Larry Swindell stated she had her first intimate affair with Hughes at about this time, as the flight and film impresario/Lothario was seeking a new leading lady for his upcoming air epic "Hell's Angels." (Greta Nissen had been cast in the role when the movie was planned as a silent, but Hughes feared her Swedish accent would make her character less believable in its conversion to sound and sought a replacement; Jean Harlow ultimately got the part.) Swindell said Howard and Carole conducted their brief affair in airtight secrecy, and it's highly likely that any physical activity between them took place in Hughes' office.
This affair was the subject of a "Carole & Co." entry some years back (http://carole-and-co.livejournal.com/57165.html) and later was brought up in the "Dear Old Hollywood" blog nearly two years ago (http://dearoldhollywood.blogspot.com/2011/02/howard-hughes-headquarters.html). Now the building is in the fashion, art and gift business, hosting a retail and online site called "Just One Eye" (http://justoneeye.com). Its co-founder is a fashion maven named Paola Russo:
You can learn more about "Just One Eye" at http://la-confidential-magazine.com/style/articles/just-one-eye-boutique-opens-in-a-storied-space.