the ceiling of a building with a blue sky in the background

As a former software tester, I am all about the details, and going to Paris and seeing all of the beautiful architecture where it's so apparent that the architects were all about the details in their buildings they designed, and that includes the detail in the arched ceiling of the spectacular Arc de Triomphe. It still amazes me how men were able to build these at a time when modern machinery and technology did not exist and yet are still standing for all to see. If you zoom in, you will see the flowers in squares are different. Truly astounding!