You'll need to be able to read German and Classical Latin, but once those minor hurdles are overcome this is a rich collection of primary sources on early German history. I only had a brief peek but it seems to focus on ancient & medieval Germany. I guess they're written in Latin as it was the lingua franca of Europe at the time. They're organised into books with chapters and indices so it's unlikely they were written in Roman times (or at least it seems so to me).
Actually, the MGH is a collection of sources mainly for medieval Germany (of course including areas that are not German today), initially started with the intent to create a complete edited version of sources for the middle ages. They are in fact organised by type, like legal documents, letters, chronicles, etc., whereas chronicles are also organised by author.
It's an invaluable reference for everyone doing work in medieval history. By the way, the link you saved doesn't work, I'd instead use this one: http://www.mgh.de/dmgh/
The British School at Rome Archive (BSR) thanks to the Getty Foundation, made freely available digital copies of the John Bryan Ward-Perkins photographic collection. A website of the "BSR digital collections was created to present not only the photographic material (Photographs) but also other types of resources which follow into different categories: Maps, Prints, Documents, Postcards, Drawings, Paintings and Manuscripts".
But "the majority of the digital images displayed on the website are represented by the photographic prints and negatives from unique historic collections, including calotypes, glass and film negatives, slides and lantern slides."
Seems to focus more on the history of the British School at Rome rather than Roman history. Should revise the tags at this point but this summer heat here in Queensland is making me lazy...
"This is a collection of hyperlinks to digitized editions of source-documents and literature concerning early medieval Europe that can be found on the internet today. Sources listed here are all available to the public, free of charge. Currently there are 3696 entries in this collection. "
It's a rather obscure topic but you never know, they might be useful for someone. Most of the manuscripts are partial and are from the Roman period in Egypt.
An excellent collection of English translations of Greek and Latin texts. You'll also find some great biographical information on the authors that students can use to improve their source evaluations (if you teach in a system which requires that - it's massive here in Queensland).