National Register of Historical Places - Clayton County
- Provides a listing of properties, districts, and landmarks in the county. Includes architectural style and period of significance.
- http://www.historicdistricts.com/IA/Clayton/state.html

Political Graveyard: Clayton County, Iowa
- Provides brief information about politicians who were born, lived in or died in the county and cemetery listings.
- http://politicalgraveyard.com/geo/IA/CT.html