He (Which should be El, but anyway) visto is not correct, because you are talking about someone else. Yo Tengo is correct, because you are staying that you have seen.
Ustedes is formal and should be used when talking to someone you’re not so familiar with, like a stranger, or someone that should be addressed with respect, like an elderly person.
A museum was named after Eugenio de Jesus Marcano Fondeur
