The Arc de Triomphe was built to honor the great military victories won by Napoleon Bonaparte. It was completed after his death and now sits in the middle of a very busy roundabout in Paris. If you take the Metro, you can access the Arc from an underground tunnel that takes you to the entrance. Fair warning, you pay about 12 Euros, and you will immediately enter the staircase that takes you to the top. I don’t know if there is an elevator or way to access only the plaza. Back on the street level, you can walk out to a small median on the Champs Elysee to get centered pictures.