The World Digital Library makes available, for free, nearly 1200 primary documents and images from collections around the world. Sponsored by the United Nations Educational, Scientific and Cultural Organization, the mission of the World Digital Library is to promote the study and understanding of cultures. The WDL can be searched by date, era, country, continent, topic, and type of resource. In my search of the WDL I noticed that roughly half of the resources are historical maps and images. The WDL aims to be accessible to as many people as possible by providing search tools and content descriptions in seven languages. The WDL can also be searched by clicking through the map on the homepage.

Applications for Education
The World Digital Library looks like it can be a great resource for anyone that teaches history 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.

Here are some related resources that may be of interest to you:
The Places We Live – Images and Sounds of Slums
Kids Around the World – Culture Lessons for K-5
Visualizing Cultures