Sepia: Comparing Photos of Places from Then and Now

Sepia Town is a website that allows you to compare historical photographs from selected major cities (see below).

Basically, you click on a city. Then you zoom in to see thumbnails of the photographs. Once you choose a photograph, click "Then/Now" button to see a side by side comparison of the present day photo to the historical one. In addition, users can upload their own historical photos to the site. While there are limited cities right now, I would imagine this site would grow over time so check back often.