A sightseer is a person who goes on vacation and visits historic or otherwise notable places. Sightseers often take photos of monuments, buildings, bridges, and parks.
Another word for a sightseer is a tourist, although the noun sightseer implies a traveler who wants to see battle sites, famous birthplaces, or beautiful gardens with her own eyes. Unlike other vacationers who might spend a week on a beach or at an amusement park, a sightseer prefers to tour castles and monuments. The word sightseer comes from the idea of seeing the sights.