From the announcement:
As of today, all images of public-domain works in The Met collection are available under Creative Commons Zero (CC0). So whether you’re an artist or a designer, an educator or a student, a professional or a hobbyist, you now have more than 375,000 images of artworks from our collection to use, share, and remix—without restriction. This policy change to Open Access is an exciting milestone in The Met’s digital evolution, and a strong statement about increasing access to the collection and how to best fulfill the Museum’s mission in a digital age.
Explore here.