[hugh3]

San Francisco is the best one. The bright red of Alcatraz and the Golden Gate Bridge combined with the deep blue of everything south of Market.

Sydney has me confused. Who are all these locals taking photos of a few major roads south of the city. Is that big thick one Botany Road? It's not really worth photographing.

[JoeAltmaier]

Tourists take pictures of public works. People take pictures of their houses.

[hugh3]

Ah, but this is nothing like a population density map of Sydney. Sydney is huge, it stretches way off in the north and west directions. What you're looking at here is basically the areas immediately south of central Sydney -- probably only 10% of the population lives in that area (though admittedly the 10% demographically most likely to use flickr).

Besides, those major roads don't have that many people living on 'em.

[enf]

People also take a lot of pictures of local businesses, although looking at Street View for that street that also seems a little unlikely. Maybe it is one of those people with a bicycle helmet camera taking pictures of their commute every day? I'll have to take a look at the pictures and check.

[JonnieCache]

Could be where a lot of nightclubs are. People love taking tedious photos in nightclubs. And there's always a clubbing district where the tourists don't go.