I live in SW London. It's definitely suburbia, but the density is just about perfect, at least as I see it. Since about age 11 my kids were fairly free range

I live in SW London. It's definitely suburbia, but the density is just about perfect, at least as I see it. Since about age 11 my kids were fairly free range - they could hang about outside with their friends (the street is very quiet, and there's a green space opposite), cycle to their friends, or use the frequent buses and trains, though we'd drive and pick them up if they were out late. Most weeks though, my car doesn't move Monday to Friday - I cycle to the station. There's plenty of green space around, and sailing and kayaking on the River Thames. But the good public transport and ability to cycle all around only really works because housing density is high. We have a four floor town house, so plenty of floor area but a fairly small garden. When we moved here, I thought it would be for just a few years, until we could afford somewhere with more land. Living previously in California, Massachusetts and elsewhere in the UK, it wasn't really my image of an ideal place. But we've been here 20 years and although I could afford to move anywhere now, I don't want to. I'm happy here. My neighbours are my friends, everyone knows everyone else, and I feel no need to try and impress anyone with how much land I have. Anyway, my point is that there probably is an optimal density for cities, and some European cities probably come close to that optimal.