I don't have an overview, but there are various databases for greek and latin inscriptions - https://inscriptions.packhum.org/allregions https://inscriptions.pa

I don't have an overview, but there are various databases for greek and latin inscriptions - https://inscriptions.packhum.org/allregions https://inscriptions.packhum.org/allregions for example is a big one. For written materials, http://www.perseus.tufts.edu/hopper/ http://www.perseus.tufts.edu/hopper/ is pretty good, but I don't think that has rarer stuff. Compared to Chinese textual sources (where it's pretty easy to find/search gigantic digitized catalogues of old chinese texts - though I don't know much about it so maybe it's lacking in many ways once one starts delving deeper), digital humanities in european languages seems to be lagging behind. Archive.org does a lot of heavy lifting for medieval latin texts, but the disadvantage is that they're not 'digitized' in the sense of being correctly OCR-ed (which is a minefield for Medieval Latin because of all the abbreviations). You have lots of individual endeavours to catalogue various types of material, and some are really good/nice, but that they're not integrated together is a minor pity (though maybe there is some nice site that I don't know about). I'm not a professional in this field, nor that learned, I've just dabbled and experienced varying degrees of frustration/satisfaction. Maybe someone who actually has an overview/proper knowledge of the field can comment, but until they do that's my layperson perception of the landscape...