The ability to view the city over time is core to data exploration and integration within a GIS. It also allows lots of nice visuals to be created and one excellent example is Medieval Dublin – From Vikings to Tudors – an interactive DVD box set that illustrates life in Dublin between 800 and 1540 AD:
The DVD explores a 3D model of the walled city, visiting a Viking house as well as strolling down a medieval street.
For more details see http://www.medievaldublin.ie/index.php
Also, take a look at the Silverlight Deepzoom version in the hunt for something rather more seasonal…