From the article linked below:
But scholars who study Medieval Italy and the history of the Roman Catholic Church dismissed those criticisms as the product of a basic misunderstanding of both the geography and the history of Vatican City, a roughly 100-acre enclave in Rome that is the seat of the Holy See.
“The rhetoric from Trump’s team is misinformation, and it is not true,” said Gerard Mannion, a professor of Catholic Studies at Georgetown University in Washington.
“It isn’t all surrounded by walls, and it’s not like you need a separate visa or a passport to enter,” he said. “You wouldn’t know, almost, when you even entered Vatican City. There is a white line painted on the ground in St. Peter’s Square, but that kind of thing is not obvious everywhere.”
There are, to be sure, formidable walls in Vatican City, and much of of the site, including the gardens and the modest guesthouse that is home to Francis, is set behind them. But the walls do not entirely enclose the city-state, and in the modern era they are not meant to, historians said.
“Anybody can walk into St. Peter’s Square — that’s the whole point of it,” said Dr. Mannion. “It was designed to be welcoming and to draw people in like two open arms, to draw them into the heart of the church.”
https://www.nytimes.com/2016/02/20/...rump-some-point-wrongly-to-vatican-walls.html