In 1555, Pope Paul IV ordered the establishment of Rome’s Jewish Ghetto, confining the city’s Jewish population to a micro-neighborhood near Campo de’ Fiori for over three centuries. The medieval townhouses of the ghetto—once a walled quarter with gates that locked at night (seriously)—are now filled with art galleries and restaurants. Walk the main thoroughfare via Portico d’Ottavia to get to the neighborhood’s Art Nouveau masterpiece: the beautiful 20th-century Great Synagogue of Rome.