Le Paris de Philippe-Auguste [IA][Direct] -
History of the wall he built around the capital, trade, education, and architecture (in English and French).
Paris Underground: Quarries and Catacombs [IA][Direct] -
Visit Paris underground: discover the quarries and catacombs 25 meters under the street and those you can find there, from the 6 million deads to the "cataphiles". Both in french and in english.