Napoleon, in February 1806, decided his arc, in praise of French armies, should be build on a place near Chaillot barrier. A perfect place, because it was "linked by a walk called Champs-Elysées" and the arc "would perfectly and majestically close the amazing point of view we had on the Tuileries royal castle."
At the same time, Napoleon raised the arc du Carrousel. It was a smaller arc, and Napoleon didn't like it... He wanted something bigger! So they decided to raise the arc de Triomphe. Napoleon wanted to transform Paris into la plus belle ville qui existât, la plus belle ville qui ait existé mais encore la plus belle ville qui puisse exister. Is that all? They built the arc with stone from Château-Landon (yep, quarries were near Paris, it was handy!) and stone from Chérence. The building was very heavy, so they had to lay out an artificial soil (8 metres deep).
Did you know that during Napoleon and Marie-Louise's wedding, on April 1810, the arc wasn't completed? The imperial couple went under a false arc made of a skeleton covered with a canvas painting with low-reliefs (this canvas was soooo expensive): this decoration lasted just one day and was immediately destroyed! Pff, what a waste!