Frommer's
Informative guide to the various architectural styles that have predominated in Paris over the centuries.
http://www.frommers.com/destinations/paris/0062026568.html

Paris La Defense
An introduction to the business district on the outskirts of Paris.
http://www.la-defense.info/

Paris.org
A guide to the history of major buildings and monuments in Paris.
http://www.paris.org/Monuments/mon.rubrique/architecture.e.html

Paris.org
Find out more about the history and architecture of Paris' train stations.
http://www.paris.org/Gares/

Rendezvous France
Architectural highlights in Paris that are worth a detour.
http://www.rendezvousfrance.com/parisarchitecture.html

Skyscraper Page
Discover Paris' contemporary architecture.
http://www.skyscraperpage.com/

Skyscrapers.com
Contains information on the city's tallest structures.
http://www.emporis.info/en/