Maybe I'm biased by Venetian-ness - where indeed you need to be able to walk to enjoy the city and distances are all very, very close. This is the opposite end of the spectrum from London, a giant metropolis if ever there was one. It is ultimately all relative. Some of us might consider Buckingham Palace near to Parliament, others might not.

But when discussing Rome and someone tells me "near the river and Castel Sant'Angelo," I think of the area around Palazzo Gaddi - or more appropriately around the Ospedale di Santo Spirito - since it is indeed on the same side of the river as Sant'Angelo. I don't happen to associate Piazza Navona with those coordinates.