Check out the sources below, which provide a starting point for digital literature collections. Don't forget to also look through the interdisciplinary digital collections that may also contain useful texts.
By no means a comprehensive list, these digital collections of foreign texts can be used for teaching and learning languages. Some other resources you may want to consider are JSTOR articles (can be filtered by language), newspapers from other countries (sometimes available online), as well as the website Fluent in 3 Months, which often provides lists of resources for reading practice.
There is a wealth of art collections available online through the websites of museum and other cultural heritage institutions. Below is a list of potential start points. If you decide to use information or images from a website, make sure to read the Terms and Conditions to ensure that you are using the images fairly and legally.