Vatican City

Other successful piazzas are those like the Piazza San Pietro, and less successful are those like the Piazza del Risorgimento and the Piazza Cola di Rienzo.
The Piazza San Pietro obviously benefits from the grandiosity of the basilica façade by Maderno, although it largely blocks the view of the dome, and Bernini’s colonnade, which reduce the apparent size of the open square, and by the high foot traffic that keep the space from feeling barren. I prefer large open spaces to have abundant green space, since vast paving tends to collect heat and feel desolate to me, but since shade is available under the colonnade and the space is well filled, it isn’t such a problem for San Pietro. The Via della Conciliazione creates a dramatic approach to the square. There is no car traffic through the square itself, although around the square it can be difficult to cut through with the amount of cars that pass.
Piazza del Risorgimento, like many other piazzas in Rome, seems to put too much emphasis on throughput for cars and not enough on comfortable places to stop and sit as someone on foot. Scattered cafés and gelaterias around the edge of the piazza notwithstanding, nowhere in the center in the piazza is terribly hospitable, and so the piazza essentially becomes a large space dedicated to a bus stop rather than a true urban gathering space. This central space is also difficult to reach from the periphery, being blocked by a wide road used by fast-moving cars. The Piazza Cola di Rienzo, meanwhile, has the opposite issue as the Piazza Vittorio Emmanuele II and Piazza del Risorgimento, which are cut off from their surroundings by wide roads. The piazza is essentially a block of stepped-back buildings with two thickened sidewalks with outdoor café seating, so while it is much more accessible than other piazzas, it ends up not feeling like a piazza at all. It may be a more pleasant and useful condition than proper piazzas that end up not being used, but it doesn’t have the same sense of place and definition.