In the list of historical figures I’d have loved to meet, Alexis de Tocqueville (1805 – 1859) figures near the top.
Together with a close friend, he visited the United States at the age of 25 for only nine months. He went back to France and wrote a book. His book Democracy in America (in two volumes, De La Démocratie en Amérique, published 1835 and 1840) is a political science classic and essential reading for understanding America.
Here’s a bit from the wiki entry on Democracy in America:
In 1831, Alexis de Tocqueville and Gustave de Beaumont were sent by the French government to study the American prison system. In his later letters Tocqueville indicates that he and Beaumont used their official business as a pretext to study American society instead. They arrived in New York City in May of that year and spent nine months traveling the United States, studying the prisons, and collecting information on American society, including its religious, political, and economic character.