"ArchiveGrid connects you with primary source material held in archives, special collections, and manuscript collections around the world. You will find historical documents, personal papers, family histories, and more. ArchiveGrid also helps researchers contact archives to request information, arrange a visit, and order copies."
Note: much of this material is not digitized and not available online; this tool helps to identify material and where it is located.
Below are fantastic free web resources from well-respected art institutions and other authoritative sources. If what you need for your research is an article from a journal, use one of our DATABASES.