"The Great Gatsby" by F. Scott Fitzgerald was published in 1925, but only entered the public domain last month. Now it's one of the books in this project:
https://www.kickstarter.com/projects/beehivebooks/illuminated-editions
These "illuminated editions" look gorgeous (and expensive); they hint at what would be possible with a larger public domain. Of course Beehive Books relies on restrictive copyright terms to protect the new artwork--we can't seem to shake artificial scarcity even when building new things.
@eliasr
Eventually, yes; this page has an overview of the very complex conditions under which works enter the public domain:
https://copyright.cornell.edu/publicdomain
In a nutshell though, for US works, everything published in 1925 or earlier is public domain. Next year it will be 1926, and so on.
In the US, we have Disney to thank for the length of copyright terms:
https://en.wikipedia.org/wiki/Copyright_Term_Extension_Act