Why are cities so densely populated

Hello.

Some cities are densley populated becasue were they are located.

One reason is if its remote and doesnt have a lot of things humans need to surive.

And some is because there is more jobs and has better health.

Have a nice day

Asmall closed hole formed in an outwash plain or moraine. forms when a  glacier retreats then remains stationary. 

Answer islamic scholars made advancements in technology, literature, philosophy, mathematics, astronomy, and the arts during this time period;