I have a website bookmarked that has a several houses constructed out of foam core. The houses are outstanding examples of what can be done with foam core. The website is http://www.inpayne.com. This site is a husband and wife combination. When you get on the site, scroll down a little and click on Mary's Dollhouses. Then the dollhouses.
The foam core houses are a San Francisco Victorian, a San Francisco Townhouse, a Four Story Brownstone, and The condo.
I enjoy browsing through the interior of her rooms as well.