British Museum Collection Online

A research catalog on a heroic scale: around 4.5 million object records, with roughly 1.9 million images available for free non-commercial use under a Creative Commons license. The value is in the records themselves, which often carry inscriptions, findspots, acquisition history and bibliography, so a student studying a Roman coin or an Assyrian relief gets the curator's working notes rather than a caption. It is a database, not a guided experience, and the search rewards specific terms. Filter to records with images, then search by place, period or material to keep the results manageable.