St Mark's Cathedral Tower rises from the highest point of Korčula's old town. The tower is not especially tall, but the town's compact peninsula makes the view count: red-tiled roofs below, the Pelješac Channel beyond, and boats moving through the blue water around the walls.
The climb is by stairs only. It is a better viewpoint than the shorter Marco Polo tower, and you can visit it separately from the cathedral interior if you mainly want the panorama.