In French, the verb visiter means to take a (guided) tour. You do that to a museum, or a house, but that's about it.
À Paris, j'ai visité le Louvre.
In Paris, I visited the Louvre.
Marie m'a fait visiter sa nouvelle maison.
Marie gave me a tour of her new house.
To say I visited Paris, I visited France... as in you went there, well, we use the verb to go: aller. Not visiter.
Je suis allée à Paris - I visited/ went to Paris
Now, an even bigger problem, since this is so much used in English, how would you say "I visited my friend", or "my friend visited me" ?
Well, it's not visiter. At least not any longer. I've seen "l'ange Gabriel vista Marie" in the Bible... but we don't use it in modern French.
So what do we use? Same answer as above: aller (or venir if the person is coming to you)
Je suis allée (voir or chez) mon amie - I visited my friend.
Mon amie est venue (me voir or chez moi) - My friend visited me.
Now, I can hear you saying "what about rendre visite à quelqu'un"? And you are right, this is an expression we use from time to time. As often as an English speaker would use "pay a visit to someone".
My experience shows however this expression doesn't work for most students. Basically, the idea of "visiter + people" kind of stays in their head, and they soon forget the correct expression and revert to "j'ai visité mon amie".
This sounds particularly bad in French since "visiter" really brings up an exploration image... When a student tells me "j'ai visité ma grand-mère" I have a flash of "Fantastic Voyage" where Raquel Welch and her team were shrunk to explore a patient's body...
So please, spare your grand-mother, and say "je suis allée voir ma grand-mère" or "je suis allée chez ma grand-mère".
