Rome is an intensively occupied, definitively urban city. After thousands of years of concentrated human development and redevelopment, there is much hardscape, where the stony facade of one building is connected to the brick wall of the next by more stone, in the form of cobbled streets and other pavements.

In the midst of some of the most intensively hard-surfaced Roman streetscapes, vegetation also abounds, soothing to the heart and eye. There are parks, of course, and open space with trees and grass. And, delightfully, gardening on rooftops, terraces, and balconies is an art that many Roman citizens seem to have mastered, providing comfort to themselves and to the city.

On the road in Rome,