3. Arc de Triomphe. It sits in the centre of Place Charles de Gaulle which was formerly known as Place de l'Etoile.
Etoile in French is a six-sided star.
I don't doubt the correctness of the answer, but I'm mystified by the suggestion that 'etoile' is French for a six-sided star. I believe 'etoile' is simply French for star (period).
I stand corrected. Perhaps I should have written as follows in ref to Place de l"Etoile:
The Place de l'�toile is a large urban junction in Paris, France, the meeting point of twelve straight avenues (hence the name "Star Square")