Eiffel Tower is a must, of course! It is cold up there so dress warm. It is also pretty terrifying if you are afraid of heights, maybe a mimosa before heading up? This is a great spot to pick up cheap souvenirs for your friends and family back home. Gypsies sell Eiffel Tower keychains, several for a Euro. Remember to negotiate or you'll pay WAY more than they're worth!
Love lock bridge in Paris. The idea is, couples or friends go to the bridge Passerelle des Arts in Paris from all around the world. They simply write their names on a padlock and attach it to the bridges railing and then throw away the key in the Seine river to symbolize their undying love. I would die if I actually got to do this.
This is a bridge in Paris. You hang locks on it with the name of you & your boyfriend/girlfriend/bestfriend then throw the key into the river. So even though the friend/relationship may end, you can’t remove the lock. It stays there forever, as relevance to someone once a part of your life. -- Totally just added this to my bucket list!