Famous to us. You ask the average American to name a famous coin collection, they have no idea. They are more likely to know and name a famous telescope !
When I think of famous collections, these come to mind within 30 seconds: Eliasberg.... Norweb.....Bass....the 1930's and 1940's oldtimers who dealt with the great dealers Mehl, Kosoff, Kreisberg, etc.......Hansen (but I don't know exactly what he has besides some top Saints).....Half Dome (not sure who started this one but the name sticks with me because of the California hiking mountain)....Simpson......and now I think of our friend, Elite Collection (only 1933 DE, #3 at worst 1907 UHR).