Demir Kapija Canyon is the place's headline. The Vardar River cuts through a narrow limestone gate just outside town, with cliffs high enough to pull in climbers and birdwatchers as well as drivers who only meant to stop for a view.
Walk short sections if you are not equipped for a longer hike. The canyon is also a protected natural area, so it rewards patience: look up from the road and the rock faces are often more interesting than the traffic below.