Some cool coin collections in Google Art Project
https://www.google.com/culturalinstitute/browse/coins
Numismatic Museum in Athens:
https://www.google.com/culturalinstitute/u/0/collection/numismatic-museum?projectId=art-project
Münzkabinett, Staatliche Kunstsammlungen Dresden:
https://www.google.com/culturalinstitute/u/0/collection/munzkabinett-coin-cabinet?projectId=art-project
Super high res