There are two iconic arches in Paris, the Arc de Triomphe is very well known, the Grande Arche at La Défense perhaps less so. The Arc is at the center of Paris, and La Defense is on the western outskirts, however they are connected in a straight line and face one another directly, which is a pretty cool piece of urban planning. Here are a few pictures of each.
The Arc de Triomphe
The Grande Arche at La Defénse
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