Classical French architecture is a mix of diverse influences, some of them very old, that have created several of the most beautiful monuments in the world. Do some research on the history of French architecture and jot down some key points on this topic in English. Your answer should include the following points:

the key features of classical French architecture
architectural styles
a French architectural innovation (with its date of construction) that stunned the world at the time
a recent French architect and one of his famed buildings