If you go to findagrave.com, you can find out. This genealogical resource lists five million gravesites of both the famous and the obscure. Only 5,000 graves at the site are considered famous (that’s one in a thousand). But wait, there’s more.
You can mimic an actual cemetery visit online, and leave notes and “virtual flowers” on a grave record (thousands of such flowers are placed daily). Negative comments about the dead are not permitted, and are removed. Some graves, like Hitler’s, are not allowed to accept notes or flowers.