user generated content

Histografica is an interesting resource of user contributed media - they are aming to build a large collection of historical photographstied to the geographic location and time period; so you can search for photos by both time range and location. 

For exmple, searching on Washngton DC pre 1904, I found this photo of the Smithsonian Institution from 1898

You can help grow it by either sharing your photos or adding helpful information to exisiting ones via the comments form.