This page features several aggregated archives broadly focused on Europe. Please be sure to use the tips in the side bar to search for specific archives, libraries, and collections dedicated to your specific nation or region of study. This page is just a starting point.
Most nations have a national library or national archive that houses historical documents. Many of these libraries provide English translations of their sites and digitized records. Try creating a search with a search engine using the terms "NAME OF COUNTRY" and "national library" to find these resources.