World Digital Library is a resource that I started using back in 2009. At that time it was just a small collection of about 1,200 digitized primary source artifacts from libraries around the world. Today, the World Digital Library hosts more than 19,000 digitized primary source artifacts to view and download.
As you'll see in the video embedded below you can search the WDL by date, era, country, continent, topic, and type of resource. But my favorite way to explore the WDL is by browsing through the interactive maps that are available when you click on the globe icon in the site's header. The WDL aims to be accessible to as many people as possible by providing search tools and content descriptions in multiple languages.
Applications for Education
The World Digital Library can be a great resource for anyone that teaches history and or cultural studies. The wealth of image based resources along with the document based resources makes the WDL appropriate for use with most age groups.