Attraction in Rome

Built on the footprint of a Roman stadium, which is why it is a long oval rather than a square, with Bernini's Four Rivers fountain in the middle. The cafés on it charge for the position; the streets one block west do not. Best in the evening, and the natural place to end a walk through the old centre.

A baroque waterfall wedged into a small square, and far bigger in person than photographs suggest. Crowded from mid-morning until late; genuinely worth seeing at seven in the morning or after midnight, when it is lit and nearly empty. A ten-minute stop rather than a destination, and on the walk between the Pantheon and the Spanish Steps.