Sightseeing is walking around a new city to look at its famous places. Go sightseeing, a sightseeing tour, a day of sightseeing.
The word carries a faint condescension — travellers like to say they are not doing it — though seeing the famous things is mostly why anybody goes. Sightseeing fatigue is real, and three or four sights in a day is about the limit of attention.
1nounsightseeingVisiting the famous places of a city as a visitor.
“We spent the morning sightseeing in Rome and saw the Colosseum and the Trevi Fountain.”
sightseeing is an activity.
Sight plus seeing, a compound of the early nineteenth century, when travel for pleasure became common.
From sight + seeing.
Etymology from Wiktionary, CC BY-SA