给定一篇英文文章，将其中出现的所有人名和地名提取出来，并将它们用“_”符号连接到一起。
In the summer of 1991, John visited Paris, where he saw the Louvre and the Eiffel Tower. He then traveled to Rome to see the Colosseum and the Vatican.
John_Paris_Louvre_Eiffel_Tower_Rome_Colosseum_Vatican